US20180115286A1 - Pvt invariant peaking stage for continuous time linear equalizer - Google Patents
Pvt invariant peaking stage for continuous time linear equalizer Download PDFInfo
- Publication number
- US20180115286A1 US20180115286A1 US15/332,830 US201615332830A US2018115286A1 US 20180115286 A1 US20180115286 A1 US 20180115286A1 US 201615332830 A US201615332830 A US 201615332830A US 2018115286 A1 US2018115286 A1 US 2018115286A1
- Authority
- US
- United States
- Prior art keywords
- coupled
- variable resistance
- transistor
- resistance
- variable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 claims abstract description 30
- 239000003990 capacitor Substances 0.000 claims abstract description 28
- 230000003213 activating effect Effects 0.000 claims 1
- 235000012431 wafers Nutrition 0.000 abstract 3
- 230000007850 degeneration Effects 0.000 description 11
- 230000003068 static effect Effects 0.000 description 9
- 238000012546 transfer Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000003190 augmentative effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
- H03F1/301—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in MOSFET amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/42—Modifications of amplifiers to extend the bandwidth
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/189—High frequency amplifiers, e.g. radio frequency amplifiers
- H03F3/19—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
- H03F3/193—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only with field-effect devices
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/189—High frequency amplifiers, e.g. radio frequency amplifiers
- H03F3/19—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
- H03F3/195—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only in integrated circuits
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit
- H03F3/45197—Pl types
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
- H04L25/03057—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception with a recursive structure
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/297—Indexing scheme relating to amplifiers the loading circuit of an amplifying stage comprising a capacitor
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/447—Indexing scheme relating to amplifiers the amplifier being protected to temperature influence
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/552—Indexing scheme relating to amplifiers the amplifier being made for video applications
Definitions
- This invention generally relates to electronic devices and equalizing power distribution using a peaking stage in an amplifier.
- Peaking amplifiers are used in electronic systems where a peaking characteristic in a frequency transfer function is needed (e.g., higher gain at high frequencies than at low frequencies).
- One important application for peaking amplifiers is signal equalization. For instance, when high-speed (e.g., multi-Gb/s) digital data streams are transferred over electrical serial links, the transmitted pulses are distorted by high-frequency losses in the channel media. To improve the maximum data rates of such links, it is preferred to equalize the frequency response of the channel so that the pulse distortion is reduced. For this reason, the receivers of modern high-speed data communication links commonly employ peaking amplifiers, which boost the high-frequency components of the received signal that were attenuated by the channel response.
- One embodiment described herein is a peaking stage that includes a first variable resistance comprising a first end coupled to a voltage rail, a second variable resistance comprising a first end coupled to the voltage rail, and a resistance control circuit comprising a first comparator and a first analog to digital converter (ADC) configured to generate a first digital signal for setting a first resistance value of the first variable resistance and a second resistance value of the second variable resistance.
- the peaking stage also includes a first transistor coupled to a second end of the first variable resistance and a second transistor coupled to a second end of the second variable resistance, where the first and second transistors are configured to generate equalized output signals based on respective input signals.
- the peaking stage includes a first variable resistance comprising a first end coupled to a voltage rail, a second variable resistance comprising a first end coupled to the voltage rail, and a first resistance control circuit comprising a first comparator configured to generate a first signal for setting a first resistance value of the first variable resistance and a second resistance value of the second variable resistance.
- the peaking stage also includes a first transistor coupled to a second end of the first variable resistance and a second transistor coupled to a second end of the second variable resistance, where the first and second transistors are configured to generate equalized output signals based on respective input signals received by the amplifier.
- the peaking stage includes a first variable resistance comprising a first end coupled to a voltage rail, a second variable resistance comprising a first end coupled to the voltage rail, and a resistance control circuit comprising a comparator configured to generate a first signal for setting a first resistance value of the first variable resistance and a second resistance value of the second variable resistance.
- the peaking stage includes a first transistor coupled to a second end of the first variable resistance and a second transistor coupled to a second end of the second variable resistance, wherein the first and second transistors are configured to generate equalized output signals based on respective input signals received by the amplifier.
- FIG. 1 illustrates a system that includes peaking amplifiers, in accordance with an embodiment described herein;
- FIG. 2A illustrates a peaking stage in an amplifier in accordance with an embodiment described herein;
- FIG. 2B illustrates a transfer function for the peaking stage in FIG. 2A in accordance with an embodiment described herein;
- FIG. 3 illustrates a reference current generator for a peaking stage in accordance with an embodiment described herein;
- FIG. 4 illustrates a load impedance control generator for a peaking stage in accordance with an embodiment described herein;
- FIG. 5 illustrates a variable resistor for the load impedance control generator in accordance with an embodiment described herein.
- FIG. 6 illustrates a degeneration resistance control generator in accordance with an embodiment described herein.
- FIG. 7 illustrates a variable resistor for the degeneration resistance control generator in accordance with an embodiment described herein.
- FIG. 8 illustrates a peaking stage for an amplifier in accordance with an embodiment described herein.
- Various embodiments of the present invention provide input devices and methods that facilitate improved usability.
- Some signals in the input device may have power distributed across multiple frequencies or bands. However, the power may not be distributed equally across the frequencies—e.g., a lower frequency may have more power than a higher frequency.
- an amplifier may include a peaking stage which has a gain that varies across a frequency band. Thus, the peaking stage can adjust the signals so that the power distribution between frequencies is similar.
- Frequency characteristics of the peaking stage can vary depending on variations in the process used to fabricate the peaking stage.
- the peaking stage may be formed in an integrated circuit and include different capacitive elements and poly resistors which affect the frequency characteristics of the peaking stage.
- the capacitive elements and resistors may have different values, thereby changing the frequency characteristics of the peaking stage.
- the gain of the peaking stages formed on the wafer may vary depending on where the peaking stages were formed.
- the embodiments herein describe a peaking stage that is invariant of the process variation. That is, one or more of the frequency characteristics of the peaking stages do not vary as the values of a capacitive element or resistor change. As such, peaking stages formed in different process corners on the wafer have the same frequency characteristics, and thus, function in a similar manner.
- the peaking stage includes a variable resistance that is controlled by resistance control circuit that includes a comparator and an analog-to-digital converter (ADC) which generate a digital control signal that adjusts the resistance value of the variable resistance.
- ADC analog-to-digital converter
- FIG. 1 illustrates a system 100 that includes peaking amplifiers 115 , in accordance with an embodiment described herein.
- the system 100 includes cameras 110 coupled to the peaking amplifiers 115 which in turn provide equalized signals to a gesture recognition module 120 .
- the peaking amplifiers 115 and the gesture recognition module 120 are disposed on an integrated circuit—e.g., a system on chip (SOC).
- SOC system on chip
- the SOC can be coupled to the high-speed video cameras 110 via connection cables.
- the cameras 110 capture high-definition images of gestures or motion made by a hand 105 of a user which typical requires a high bandwidth.
- the data speed at which the data captured by the cameras 110 is transmitted to the gesture recognition module 120 may be between 1-10 GHz.
- the channel insertion loss of the high speed data signals transmitted by the cameras 110 means that the signals received by the gesture recognition module 120 are difficult to recover.
- the channel insertion loss may result in poor power distribution among the frequencies in the high speed data signals—i.e., the signals are not equalized.
- the high speed signals are transmitted to respective peaking amplifiers 115 which equalize the power distribution of the signals which make the signals easier to recover at the gesture recognition module 120 .
- the gesture recognition module 120 After receiving the signals, the gesture recognition module 120 processes the data to identify different gestures of the hand 105 . Because two cameras 110 are used, the module 120 can identify gestures in 3-D motion capture rather than just 2-D. In one embodiment, the system 100 is used in an augmented reality or virtual reality application. However, the peaking amplifiers 115 described herein are not limited to a system that performs gesture recognition, and instead, may be used in any system where data signals have poor power distribution.
- FIG. 2A illustrates a peaking stage 200 in an amplifier in accordance with an embodiment described herein.
- the circuitry in the peaking stage 200 may be disposed in an integrated circuit that was formed on a wafer. When processing the wafer, hundreds or thousands of the peaking stages 200 may be formed in parallel on the wafer. Once formed, the wafer is cleaved into separate integrated circuits which may include one or more amplifiers that each includes the peaking stage 200 .
- the values of the capacitors and/or resistors in the peaking stage 200 can affect the frequency characteristics of the stage 200 which dictate the gain of the peaking stage 200 across a band of frequencies.
- the peaking stage 200 includes variable resistors 205 and 210 which compensate for fluctuations in the values of the capacitors and/or resistors as a result of process variations when forming the peaking stage 200 .
- Positive and negative input signals are received at the gates of a first transistor 215 and a second transistor 220 (e.g., an induction channel MOSFETs).
- the peaking stage 200 equalizes these signals—i.e., adjusts the distribution of power across the frequencies in the signals for a more even power distribution.
- the positive and negative outputs (OP and ON) of the peaking stage 200 have a more even or equal distribution of power across the frequencies relative to the input signals.
- the peaking stage 200 also includes variable resistances 225 and 230 that are disposed in series between the first transistor 215 and the second transistor 220 . Like the variable resistances 205 and 210 , the variable resistances 225 and 230 can be controlled to compensate for capacitance and resistance values that vary depending on process variation. However, in other embodiments, the variable resistances 225 and 230 may be replaced by one or more static (i.e., unchanging) resistors.
- the peaking stage 200 also includes a variable capacitance 235 and two static resistors R 1 and R 2 which are in parallel with the variable resistors 225 and 230 . The peaking stage 200 can be disabled by disconnecting the variable capacitor 235 from the circuit.
- the peaking stage 200 includes a third transistor 240 and a fourth transistor 245 whose gates are coupled to a biasing voltage (V BIAS ) for biasing the peaking stage 200 .
- the third transistor 240 and fourth transistor 245 are coupled to a reference voltage—e.g., ground.
- Equation 1 defines the gain (A 0 ) of the peaking stage 200 , where R L is the resistance value of one of the variable resistances 205 or 210 and R S is the resistance value of one of the variable resistances 225 or 230 .
- a 0 g m ⁇ R L 1 + g m ⁇ R S ( 1 )
- Equation 2 defines the peaking frequency ( ⁇ Z ) of the peaking stage 200 .
- Equation 3 defines a first pole frequency ( ⁇ p1 ) of the peaking stage 200 .
- Equation 4 defines a second pole frequency ( ⁇ p2 ) of the peaking stage 200 .
- the values of the gain (A 0 ) peaking frequency ( ⁇ Z ), the first pole frequency ( ⁇ p1 ), and the second pole frequency ( ⁇ p2 ) are the frequency characteristics of the peaking stage 200 . As shown by Equations 2, 3, and 4, the values of these frequencies depend on the values of R S , R L , C s , and C L . However, because the resistances R S , R L (i.e., variable resistances 205 , 210 , 225 , and 230 ) are variable rather than static, the peaking stage 200 can adjust these resistances to compensate for process variations.
- variable resistances 205 , 210 , 225 , and 230 where fixed resistances, the values of the frequency characteristics of the peaking stage 200 would vary depending on process variations. However, as described below, the variable resistances 205 , 210 , 225 , and 230 can be adjusted such that the frequency characteristics are invariant to process variations.
- a process invariant peaking stage is useful for many different applications such as a high-speed SERDES, high-speed display applications for the input device 100 , and the like.
- FIG. 2B is a chart 250 which illustrates a transfer function for the peaking stage in FIG. 2A in accordance with an embodiment described herein.
- the Y axis of the chart 250 illustrates the gain of the peaking stage while the X axis illustrates the frequency of the signal inputted to the peaking stage.
- the peaking stage operates in a low frequency gain region where the gain is relatively flat (i.e., A 0 ). However, at the peaking frequency, the gain increases until the first pole frequency ( ⁇ p1 ) is reached (also referred to as the saturation frequency). Between the first pole frequency and the second pole frequency ( ⁇ p2 ), the gain of the peaking stage is again relatively flat.
- the gain of the peaking stage between the first and second pole frequencies can be expressed as:
- the gain of the peaking stage begins to decrease.
- the peaking stage can equalize power distribution between the frequencies in a signal. For example, if the higher frequencies in a signal (e.g., frequencies between the first and second pole frequencies) have less power than the frequencies below the peaking frequency, inputting this signal into the peaking stage increases the power of the higher frequencies relative to the lower frequencies.
- the terms “equalizer,” “equalization,” “equalize,” or “equalizing” does not mean the peaking stage ensures the power across all frequencies is precisely equal, but rather outputs a signal with improved distribution of the power across its frequencies relative to an input signal.
- FIG. 3 illustrates a reference current generator 300 for a peaking stage in accordance with an embodiment described herein.
- the reference current generator 300 outputs one or more reference currents which are used in other circuits in the peaking stage as described below.
- the reference current generator 300 includes a first current mirror formed by transistor 305 and 310 and a second current mirror formed by transistors 315 and 322 .
- the drain of transistor 345 generates a positive reference current (I REFP ) while the drain of transistor 340 generates a negative reference current (I REFN ).
- the reference current generator 300 is also coupled to a startup circuit 335 which is used to start the generator 300 when the peaking stage is turned on or initialized to ensure the circuit does not stay in the zero current state, and the startup circuit 335 will shut off itself when the generator 300 is in a normal working state.
- the reference current I REF is proportional to the square of the frequency (f) of the clock and the value of capacitor C 1 as shown in the following equation:
- the reference current also changes.
- the source of transistor 322 is coupled to a switched capacitor network that forms an equivalent resistance 320 (R EQ ).
- the switches 325 and 330 are activated using a non-overlapped signal where the switches 325 and 330 are never on at the same time. However, the switches 325 and 330 may both be off at the same time.
- the switch 325 When the switch 325 is off (deactivated) and the switch 330 is on (activated) as shown in FIG. 3 , the capacitor C 1 is discharged. Conversely, when the switch 325 is on and the switch 330 is off, the capacitor C 1 is charged in parallel with the capacitor C 2 .
- the value of the equivalent resistance 320 is proportional to (f*C 1 ) and the value of the reference current is as follows:
- I REF ( fC 1 ) 2 1 2 ⁇ ⁇ ⁇ ⁇ C ox ′ ⁇ ( W L ) ⁇ ( 1 - 1 m ) 2 ( 7 )
- Equation 7 can be simplified using a ratio of constants B 0 as:
- I REF B 0 ( fC 1 ) 2 ⁇ ( fC 1 ) 2 (8)
- the gain of the reference current generator 300 is also proportional to the clock frequency and the capacitor C 1 . As such, these values are dependent on the clock frequency (which is based on a reference clock such as a crystal oscillator) and the value of the capacitor C 1 which can vary depending on process variations.
- FIG. 4 illustrates a load impedance control generator 400 (e.g., a resistance control circuit) for a peaking stage in accordance with an embodiment described herein.
- the load impedance control generator 400 uses the positive reference current (i.e., I REFP ) generated by the reference current generator 300 in FIG. 3 to control the variable resistance 401 (R EQP ) in the peaking stage. That is, the load impedance control generator 400 generates a digital control signal 430 which adjusts the value of the variable resistance 401 .
- the digital control signal 430 can also control the variable resistances 205 and 210 (i.e., R EQP1 and R EQP2 ) in the peaking stage shown in FIG. 2 .
- the load impedance control generator 400 includes a switched capacitor network that forms an equivalent resistance 405 which operates in a similar manner as the switched capacitor network shown in FIG. 3 .
- the capacitance value of C 0 is greater than the value of C 3 to keep the voltage ripple at node V 1 small.
- the equivalent resistance 405 includes a first switch 415 and a second switch 410 which, in one embodiment, are driven by non-overlapping signals.
- the switched capacitor network outputs a current I 1 while the variable resistor 401 outputs the current I 2 . Both of the currents I 1 and I 2 are fed into a current mirror formed by transistors 440 and 445 . To make these currents equal, the load impedance control generator 400 feeds voltages V 1 and V 2 into respective inputs of a comparator 420 .
- the output of the comparator 420 varies according to the difference between the currents I 1 and I 2 .
- the output of the comparator 420 is coupled to an analog to digital converter (ADC) 425 which generates the digital control signal 430 which varies according to the difference between the currents I 1 and I 2 .
- ADC analog to digital converter
- the digital control signal 430 adjusts the value of the variable resistance 401 until the currents I 1 and I 2 are equal.
- the resistance values of the variable resistance 401 and the equivalent resistance 405 are equal.
- the resistance value of variable resistance 401 can be expressed as:
- the value of the variable resistance 401 varies according to the value of the capacitor C 3 which can vary in response to process variations and the frequency (f) of the clock.
- FIG. 5 illustrates the variable resistance 401 for the peaking stage 200 in accordance with an embodiment described herein.
- the variable resistance 401 receives the digital control signal 430 which activates or deactivates a plurality of transistors 505 .
- Each of the transistors 505 is coupled to a respective fixed, or static, resistor 510 .
- the value of the digital control signal 430 determines the number of the transistors 505 that are activated which combines the resistors 510 in parallel. In this manner, the load impedance control generator can alter the variable resistance 401 in the peaking stage 200 shown in FIG. 2 .
- the resistors 510 are poly resistors, and as such, the value of the resistors 510 may change because of process variations.
- the load impedance control generator 400 can adjust the number of resistors 510 coupled in parallel, thereby changing the total resistance value of the variable resistance 401 .
- the load impedance control generator 400 can compensate for these changes using the digital control signals 430 .
- the circuit schematic for the variable resistance 401 in the load impedance control generator 400 is also used for the variable resistance 205 and 210 in the peaking stage 200 .
- the same digital control signal 430 sets the resistance values of the variable resistances 401 , 205 , and 210 to the same value.
- FIG. 6 illustrates a degeneration resistance control generator 600 in accordance with an embodiment described herein.
- the degeneration resistance control generator 600 is similar to the load impedance control generator 400 shown in FIG. 4 .
- the peaking stage uses the degeneration resistance control generator 600 to control the variable resistance 225 and 230 (i.e., R EQN1 and R EQN2 ) shown in FIG. 2 .
- the degeneration resistance control generator 600 uses the negative reference current (I REFN ), a switched capacitor network (i.e., equivalent resistance 620 ), a first comparator 605 , a second comparator 625 , and a ADC 610 to output a digital control signal 615 that varies the resistance of a variable resistance 601 .
- the digital control signal 615 also controls the variable resistances 225 and 230 in the peaking stage.
- FIG. 7 illustrates the variable resistance 601 for the degeneration resistance control generator 600 in accordance with an embodiment described herein.
- the variable resistance 601 receives the digital control signal 615 which activates or deactivates a plurality of transistors 710 .
- Each of the transistors 710 is coupled to a respective fixed or static resistor 705 (e.g., poly resistors).
- the value of the digital control signal 615 determines the number of the transistors 710 that are activated which combines the resistors 705 in parallel. In this manner, the degeneration resistance control generator can alter the variable resistance 601 in the peaking stage 200 shown in FIG. 2 .
- the value of the resistors 705 changes because of process variations used to form the peaking stage.
- the degeneration resistance control generator 600 can adjust the number of resistors 705 coupled in parallel, thereby changing the total resistance value of the variable resistance 601 .
- the degeneration resistance control generator 600 can compensate for these changes using the digital control signals 615 .
- the circuit schematic for the variable resistance 601 is also used for the variable resistances 225 and 230 in the peaking stage 200 .
- the same digital control signal 615 sets the resistance values of the variable resistances 601 , 225 , and 230 to the same value.
- FIG. 8 illustrates a peaking stage 800 for an amplifier in accordance with an embodiment described herein.
- the peaking stage 800 is the same as the peaking stage 200 shown in FIG. 2 except that the peaking stage 800 illustrates the digital control signal 430 outputted by the load impedance control generator and the digital control signal 615 outputted by the degeneration resistance control generator.
- the digital control signals 430 adjust the values of the variable resistances 205 and 210 to the same resistance value while the digital control signal 615 adjusts the values of the variable resistances 225 and 230 to the same resistance value.
- respective digital control signals are shown for variable resistance 205 and 210 and for variable resistances 225 and 230
- the peaking stage 800 may generate a digital control signal for each of the variable resistances 205 , 210 , 225 , and 230 individually.
- the gain of the peaking stage 800 can be expressed as:
- Equation 11 the values B 1 , B 2 , and B 3 represent constant ratios that do not change in response to process variations. Equation 11 can be further reduced as follows:
- a 0 B 1 ⁇ B 2 ⁇ B 5 1 + B 1 ⁇ B 2 ⁇ B 3 ( 12 )
- the gain of the peaking stage 800 does not depend on the value of the capacitors or resistors in the underlying circuitry. Instead, the gain depends on the value of the constants which do not change depending on process variation. Thus, the peaking stage 800 has a gain which is invariant to process variations.
- the peaking frequency of the peaking stage 800 can be expressed as:
- Equation 13 illustrates that the peaking frequency of the peaking stage 800 is invariant to process variations.
- the peaking frequency depends on the clock frequency (which depends on a crystal oscillator that generates the clock) and the constant ratios B 3 and B 4 .
- the peaking frequency is unaffected.
- the first pole frequency of the peaking stage 800 can be expressed as:
- first pole frequency depends on the clock frequency and the constant B ratios. As such, the first pole frequency is invariant to process variation and is unaffected as the values of the underlying static resistors and capacitive elements changes.
- the second pole frequency of the peaking stage 800 can be expressed as:
- the second pole frequency depends on the capacitance C 3 and C L thus may vary depending on process variation.
- the second pole frequency is not as important as the gain, peaking frequency, and the first pole frequency of the peaking stage 800 which are invariant to the processing corner in which the peaking stage 800 was fabricated.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Amplifiers (AREA)
Abstract
Description
- This invention generally relates to electronic devices and equalizing power distribution using a peaking stage in an amplifier.
- Peaking amplifiers are used in electronic systems where a peaking characteristic in a frequency transfer function is needed (e.g., higher gain at high frequencies than at low frequencies). One important application for peaking amplifiers is signal equalization. For instance, when high-speed (e.g., multi-Gb/s) digital data streams are transferred over electrical serial links, the transmitted pulses are distorted by high-frequency losses in the channel media. To improve the maximum data rates of such links, it is preferred to equalize the frequency response of the channel so that the pulse distortion is reduced. For this reason, the receivers of modern high-speed data communication links commonly employ peaking amplifiers, which boost the high-frequency components of the received signal that were attenuated by the channel response.
- One embodiment described herein is a peaking stage that includes a first variable resistance comprising a first end coupled to a voltage rail, a second variable resistance comprising a first end coupled to the voltage rail, and a resistance control circuit comprising a first comparator and a first analog to digital converter (ADC) configured to generate a first digital signal for setting a first resistance value of the first variable resistance and a second resistance value of the second variable resistance. The peaking stage also includes a first transistor coupled to a second end of the first variable resistance and a second transistor coupled to a second end of the second variable resistance, where the first and second transistors are configured to generate equalized output signals based on respective input signals.
- Another embodiment described herein is an amplifier that includes a peaking stage. The peaking stage includes a first variable resistance comprising a first end coupled to a voltage rail, a second variable resistance comprising a first end coupled to the voltage rail, and a first resistance control circuit comprising a first comparator configured to generate a first signal for setting a first resistance value of the first variable resistance and a second resistance value of the second variable resistance. The peaking stage also includes a first transistor coupled to a second end of the first variable resistance and a second transistor coupled to a second end of the second variable resistance, where the first and second transistors are configured to generate equalized output signals based on respective input signals received by the amplifier.
- Another embodiment described herein is an integrated circuit that includes a peaking stage. The peaking stage includes a first variable resistance comprising a first end coupled to a voltage rail, a second variable resistance comprising a first end coupled to the voltage rail, and a resistance control circuit comprising a comparator configured to generate a first signal for setting a first resistance value of the first variable resistance and a second resistance value of the second variable resistance. The peaking stage includes a first transistor coupled to a second end of the first variable resistance and a second transistor coupled to a second end of the second variable resistance, wherein the first and second transistors are configured to generate equalized output signals based on respective input signals received by the amplifier.
-
FIG. 1 illustrates a system that includes peaking amplifiers, in accordance with an embodiment described herein; -
FIG. 2A illustrates a peaking stage in an amplifier in accordance with an embodiment described herein; -
FIG. 2B illustrates a transfer function for the peaking stage inFIG. 2A in accordance with an embodiment described herein; -
FIG. 3 illustrates a reference current generator for a peaking stage in accordance with an embodiment described herein; -
FIG. 4 illustrates a load impedance control generator for a peaking stage in accordance with an embodiment described herein; -
FIG. 5 illustrates a variable resistor for the load impedance control generator in accordance with an embodiment described herein; and -
FIG. 6 illustrates a degeneration resistance control generator in accordance with an embodiment described herein. -
FIG. 7 illustrates a variable resistor for the degeneration resistance control generator in accordance with an embodiment described herein. -
FIG. 8 illustrates a peaking stage for an amplifier in accordance with an embodiment described herein. - To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. The drawings referred to here should not be understood as being drawn to scale unless specifically noted. Also, the drawings are often simplified and details or components omitted for clarity of presentation and explanation. The drawings and discussion serve to explain principles discussed below, where like designations denote like elements.
- The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or its application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
- Various embodiments of the present invention provide input devices and methods that facilitate improved usability. Some signals in the input device may have power distributed across multiple frequencies or bands. However, the power may not be distributed equally across the frequencies—e.g., a lower frequency may have more power than a higher frequency. To equalize the power distribution, an amplifier may include a peaking stage which has a gain that varies across a frequency band. Thus, the peaking stage can adjust the signals so that the power distribution between frequencies is similar.
- Frequency characteristics of the peaking stage, however, can vary depending on variations in the process used to fabricate the peaking stage. For example, the peaking stage may be formed in an integrated circuit and include different capacitive elements and poly resistors which affect the frequency characteristics of the peaking stage. Depending on where on a wafer the peaking stage is formed, the capacitive elements and resistors may have different values, thereby changing the frequency characteristics of the peaking stage. Thus, the gain of the peaking stages formed on the wafer may vary depending on where the peaking stages were formed.
- The embodiments herein describe a peaking stage that is invariant of the process variation. That is, one or more of the frequency characteristics of the peaking stages do not vary as the values of a capacitive element or resistor change. As such, peaking stages formed in different process corners on the wafer have the same frequency characteristics, and thus, function in a similar manner. In one embodiment, the peaking stage includes a variable resistance that is controlled by resistance control circuit that includes a comparator and an analog-to-digital converter (ADC) which generate a digital control signal that adjusts the resistance value of the variable resistance. As a result, even as the values of the physical capacitive elements and resistors change relative to other peaking circuits formed on the same wafer, each peaking stage can compensate for this process variation by adjusting the resistance value of the variable resistance thereby maintaining the desired frequency characteristics.
-
FIG. 1 illustrates asystem 100 that includes peaking amplifiers 115, in accordance with an embodiment described herein. Specifically, thesystem 100 includes cameras 110 coupled to the peaking amplifiers 115 which in turn provide equalized signals to agesture recognition module 120. In one embodiment, the peaking amplifiers 115 and thegesture recognition module 120 are disposed on an integrated circuit—e.g., a system on chip (SOC). The SOC can be coupled to the high-speed video cameras 110 via connection cables. In operation, the cameras 110 capture high-definition images of gestures or motion made by a hand 105 of a user which typical requires a high bandwidth. For example, the data speed at which the data captured by the cameras 110 is transmitted to thegesture recognition module 120 may be between 1-10 GHz. - The channel insertion loss of the high speed data signals transmitted by the cameras 110 means that the signals received by the
gesture recognition module 120 are difficult to recover. For example, the channel insertion loss may result in poor power distribution among the frequencies in the high speed data signals—i.e., the signals are not equalized. Instead, the high speed signals are transmitted to respective peaking amplifiers 115 which equalize the power distribution of the signals which make the signals easier to recover at thegesture recognition module 120. - After receiving the signals, the
gesture recognition module 120 processes the data to identify different gestures of the hand 105. Because two cameras 110 are used, themodule 120 can identify gestures in 3-D motion capture rather than just 2-D. In one embodiment, thesystem 100 is used in an augmented reality or virtual reality application. However, the peaking amplifiers 115 described herein are not limited to a system that performs gesture recognition, and instead, may be used in any system where data signals have poor power distribution. -
FIG. 2A illustrates a peakingstage 200 in an amplifier in accordance with an embodiment described herein. In one embodiment, the circuitry in the peakingstage 200 may be disposed in an integrated circuit that was formed on a wafer. When processing the wafer, hundreds or thousands of the peaking stages 200 may be formed in parallel on the wafer. Once formed, the wafer is cleaved into separate integrated circuits which may include one or more amplifiers that each includes the peakingstage 200. As discussed above, the values of the capacitors and/or resistors in the peakingstage 200 can affect the frequency characteristics of thestage 200 which dictate the gain of the peakingstage 200 across a band of frequencies. However, the peakingstage 200 includesvariable resistors stage 200. - Positive and negative input signals (IP and IN) are received at the gates of a
first transistor 215 and a second transistor 220 (e.g., an induction channel MOSFETs). As described above, the peakingstage 200 equalizes these signals—i.e., adjusts the distribution of power across the frequencies in the signals for a more even power distribution. Thus, the positive and negative outputs (OP and ON) of the peakingstage 200 have a more even or equal distribution of power across the frequencies relative to the input signals. - The peaking
stage 200 also includesvariable resistances first transistor 215 and thesecond transistor 220. Like thevariable resistances variable resistances variable resistances stage 200 also includes avariable capacitance 235 and two static resistors R1 and R2 which are in parallel with thevariable resistors stage 200 can be disabled by disconnecting thevariable capacitor 235 from the circuit. - Moreover, the peaking
stage 200 includes athird transistor 240 and afourth transistor 245 whose gates are coupled to a biasing voltage (VBIAS) for biasing the peakingstage 200. Moreover, thethird transistor 240 andfourth transistor 245 are coupled to a reference voltage—e.g., ground. -
Equation 1 defines the gain (A0) of the peakingstage 200, where RL is the resistance value of one of thevariable resistances variable resistances -
- Equation 2 defines the peaking frequency (ωZ) of the peaking
stage 200. -
- Equation 3 defines a first pole frequency (ωp1) of the peaking
stage 200. -
- Equation 4 defines a second pole frequency (ωp2) of the peaking
stage 200. -
- The values of the gain (A0) peaking frequency (ωZ), the first pole frequency (ωp1), and the second pole frequency (ωp2) are the frequency characteristics of the peaking
stage 200. As shown by Equations 2, 3, and 4, the values of these frequencies depend on the values of RS, RL, Cs, and CL. However, because the resistances RS, RL (i.e.,variable resistances stage 200 can adjust these resistances to compensate for process variations. Put differently, if thevariable resistances stage 200 would vary depending on process variations. However, as described below, thevariable resistances input device 100, and the like. -
FIG. 2B is achart 250 which illustrates a transfer function for the peaking stage inFIG. 2A in accordance with an embodiment described herein. The Y axis of thechart 250 illustrates the gain of the peaking stage while the X axis illustrates the frequency of the signal inputted to the peaking stage. As shown, for frequencies below the peaking frequency (ωZ), the peaking stage operates in a low frequency gain region where the gain is relatively flat (i.e., A0). However, at the peaking frequency, the gain increases until the first pole frequency (ωp1) is reached (also referred to as the saturation frequency). Between the first pole frequency and the second pole frequency (ωp2), the gain of the peaking stage is again relatively flat. The gain of the peaking stage between the first and second pole frequencies can be expressed as: -
- After the second pole frequency, the gain of the peaking stage begins to decrease. Using the variable gain shown in
chart 250, the peaking stage can equalize power distribution between the frequencies in a signal. For example, if the higher frequencies in a signal (e.g., frequencies between the first and second pole frequencies) have less power than the frequencies below the peaking frequency, inputting this signal into the peaking stage increases the power of the higher frequencies relative to the lower frequencies. As used herein, the terms “equalizer,” “equalization,” “equalize,” or “equalizing” does not mean the peaking stage ensures the power across all frequencies is precisely equal, but rather outputs a signal with improved distribution of the power across its frequencies relative to an input signal. -
FIG. 3 illustrates a referencecurrent generator 300 for a peaking stage in accordance with an embodiment described herein. In one embodiment, the referencecurrent generator 300 outputs one or more reference currents which are used in other circuits in the peaking stage as described below. The referencecurrent generator 300 includes a first current mirror formed bytransistor transistors transistor 345 generates a positive reference current (IREFP) while the drain oftransistor 340 generates a negative reference current (IREFN). The referencecurrent generator 300 is also coupled to astartup circuit 335 which is used to start thegenerator 300 when the peaking stage is turned on or initialized to ensure the circuit does not stay in the zero current state, and thestartup circuit 335 will shut off itself when thegenerator 300 is in a normal working state. - The reference current IREF is proportional to the square of the frequency (f) of the clock and the value of capacitor C1 as shown in the following equation:
-
I REF∝(f*C 1)2 (6) - Thus, as the value of the capacitor C1 changes due to a process variation, the reference current also changes.
- The source of
transistor 322 is coupled to a switched capacitor network that forms an equivalent resistance 320 (REQ). The switched capacitor network includes a switch 325 (S2) and a switch 330 (S1) which are activated based on the clocking values ϕ andϕ , where f=frequency(ϕ). In one embodiment, theswitches switches switches - When the
switch 325 is off (deactivated) and theswitch 330 is on (activated) as shown inFIG. 3 , the capacitor C1 is discharged. Conversely, when theswitch 325 is on and theswitch 330 is off, the capacitor C1 is charged in parallel with the capacitor C2. By controlling the switches, the value of theequivalent resistance 320 is proportional to (f*C1) and the value of the reference current is as follows: -
-
Equation 7 can be simplified using a ratio of constants B0 as: -
I REF =B 0(fC 1)2∝(fC 1)2 (8) - Moreover, the gain of the reference
current generator 300 is also proportional to the clock frequency and the capacitor C1. As such, these values are dependent on the clock frequency (which is based on a reference clock such as a crystal oscillator) and the value of the capacitor C1 which can vary depending on process variations. -
FIG. 4 illustrates a load impedance control generator 400 (e.g., a resistance control circuit) for a peaking stage in accordance with an embodiment described herein. As shown, the loadimpedance control generator 400 uses the positive reference current (i.e., IREFP) generated by the referencecurrent generator 300 inFIG. 3 to control the variable resistance 401 (REQP) in the peaking stage. That is, the loadimpedance control generator 400 generates adigital control signal 430 which adjusts the value of thevariable resistance 401. However, as will be described inFIG. 8 , thedigital control signal 430 can also control thevariable resistances 205 and 210 (i.e., REQP1 and REQP2) in the peaking stage shown inFIG. 2 . - The load
impedance control generator 400 includes a switched capacitor network that forms anequivalent resistance 405 which operates in a similar manner as the switched capacitor network shown inFIG. 3 . In one embodiment, the capacitance value of C0 is greater than the value of C3 to keep the voltage ripple at node V1 small. Theequivalent resistance 405 includes afirst switch 415 and asecond switch 410 which, in one embodiment, are driven by non-overlapping signals. - The switched capacitor network outputs a current I1 while the
variable resistor 401 outputs the current I2. Both of the currents I1 and I2 are fed into a current mirror formed bytransistors impedance control generator 400 feeds voltages V1 and V2 into respective inputs of acomparator 420. - The output of the
comparator 420 varies according to the difference between the currents I1 and I2. The output of thecomparator 420 is coupled to an analog to digital converter (ADC) 425 which generates thedigital control signal 430 which varies according to the difference between the currents I1 and I2. Stated generally, thedigital control signal 430 adjusts the value of thevariable resistance 401 until the currents I1 and I2 are equal. As a result, the resistance values of thevariable resistance 401 and theequivalent resistance 405 are equal. Thus, the resistance value ofvariable resistance 401 can be expressed as: -
- As shown by Equation 9, the value of the
variable resistance 401 varies according to the value of the capacitor C3 which can vary in response to process variations and the frequency (f) of the clock. -
FIG. 5 illustrates thevariable resistance 401 for the peakingstage 200 in accordance with an embodiment described herein. In one embodiment, thevariable resistance 401 receives thedigital control signal 430 which activates or deactivates a plurality oftransistors 505. Each of thetransistors 505 is coupled to a respective fixed, or static,resistor 510. The value of thedigital control signal 430 determines the number of thetransistors 505 that are activated which combines theresistors 510 in parallel. In this manner, the load impedance control generator can alter thevariable resistance 401 in the peakingstage 200 shown inFIG. 2 . - In one embodiment, the
resistors 510 are poly resistors, and as such, the value of theresistors 510 may change because of process variations. However, because of the feedback loop shown inFIG. 4 where the current (or voltage) of thevariable resistance 401 is compared to the current (or voltage) outputted by theequivalent resistance 405, the loadimpedance control generator 400 can adjust the number ofresistors 510 coupled in parallel, thereby changing the total resistance value of thevariable resistance 401. Thus, even as the underlying value of thestatic resistors 510 changes, the loadimpedance control generator 400 can compensate for these changes using the digital control signals 430. - In one embodiment, the circuit schematic for the
variable resistance 401 in the loadimpedance control generator 400 is also used for thevariable resistance stage 200. In one example, the samedigital control signal 430 sets the resistance values of thevariable resistances -
FIG. 6 illustrates a degenerationresistance control generator 600 in accordance with an embodiment described herein. The degenerationresistance control generator 600 is similar to the loadimpedance control generator 400 shown inFIG. 4 . However, the peaking stage uses the degenerationresistance control generator 600 to control thevariable resistance 225 and 230 (i.e., REQN1 and REQN2) shown inFIG. 2 . To do so, the degenerationresistance control generator 600 uses the negative reference current (IREFN), a switched capacitor network (i.e., equivalent resistance 620), afirst comparator 605, asecond comparator 625, and aADC 610 to output adigital control signal 615 that varies the resistance of avariable resistance 601. As described below, in one embodiment, thedigital control signal 615 also controls thevariable resistances -
FIG. 7 illustrates thevariable resistance 601 for the degenerationresistance control generator 600 in accordance with an embodiment described herein. In one embodiment, thevariable resistance 601 receives thedigital control signal 615 which activates or deactivates a plurality oftransistors 710. Each of thetransistors 710 is coupled to a respective fixed or static resistor 705 (e.g., poly resistors). The value of thedigital control signal 615 determines the number of thetransistors 710 that are activated which combines theresistors 705 in parallel. In this manner, the degeneration resistance control generator can alter thevariable resistance 601 in the peakingstage 200 shown inFIG. 2 . - In one embodiment, the value of the
resistors 705 changes because of process variations used to form the peaking stage. However, because of the feedback loop shown inFIG. 6 where the current (or voltage) of thevariable resistance 601 is compared to the current (or voltage) outputted by theequivalent resistance 620, the degenerationresistance control generator 600 can adjust the number ofresistors 705 coupled in parallel, thereby changing the total resistance value of thevariable resistance 601. Thus, even as the underlying value of thestatic resistors 705 changes, the degenerationresistance control generator 600 can compensate for these changes using the digital control signals 615. - In one embodiment, the circuit schematic for the
variable resistance 601 is also used for thevariable resistances stage 200. In one example, the samedigital control signal 615 sets the resistance values of thevariable resistances -
FIG. 8 illustrates a peakingstage 800 for an amplifier in accordance with an embodiment described herein. The peakingstage 800 is the same as the peakingstage 200 shown inFIG. 2 except that the peakingstage 800 illustrates thedigital control signal 430 outputted by the load impedance control generator and thedigital control signal 615 outputted by the degeneration resistance control generator. In one embodiment, the digital control signals 430 adjust the values of thevariable resistances digital control signal 615 adjusts the values of thevariable resistances variable resistance variable resistances stage 800 may generate a digital control signal for each of thevariable resistances - The gain of the peaking
stage 800 can be expressed as: -
- In
Equation 11, the values B1, B2, and B3 represent constant ratios that do not change in response to process variations.Equation 11 can be further reduced as follows: -
- As illustrated by
Equation 12, the gain of the peakingstage 800 does not depend on the value of the capacitors or resistors in the underlying circuitry. Instead, the gain depends on the value of the constants which do not change depending on process variation. Thus, the peakingstage 800 has a gain which is invariant to process variations. - The peaking frequency of the peaking
stage 800 can be expressed as: -
- Like the gain, Equation 13 illustrates that the peaking frequency of the peaking
stage 800 is invariant to process variations. Here, the peaking frequency depends on the clock frequency (which depends on a crystal oscillator that generates the clock) and the constant ratios B3 and B4. Thus, as the values of the underlying static resistors and capacitive elements changes, the peaking frequency is unaffected. - The first pole frequency of the peaking
stage 800 can be expressed as: -
- Like the peaking frequency, first pole frequency depends on the clock frequency and the constant B ratios. As such, the first pole frequency is invariant to process variation and is unaffected as the values of the underlying static resistors and capacitive elements changes.
- The second pole frequency of the peaking
stage 800 can be expressed as: -
- As shown by Equation 15, the second pole frequency depends on the capacitance C3 and CL thus may vary depending on process variation. However, the second pole frequency is not as important as the gain, peaking frequency, and the first pole frequency of the peaking
stage 800 which are invariant to the processing corner in which thepeaking stage 800 was fabricated. - Thus, the embodiments and examples set forth herein were presented in order to best explain the embodiments in accordance with the present technology and its particular application and to thereby enable those skilled in the art to make and use the present technology. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the disclosure to the precise form disclosed.
- In view of the foregoing, the scope of the present disclosure is determined by the claims that follow.
Claims (23)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/332,830 US9954495B1 (en) | 2016-10-24 | 2016-10-24 | PVT invariant peaking stage for continuous time linear equalizer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/332,830 US9954495B1 (en) | 2016-10-24 | 2016-10-24 | PVT invariant peaking stage for continuous time linear equalizer |
Publications (2)
Publication Number | Publication Date |
---|---|
US9954495B1 US9954495B1 (en) | 2018-04-24 |
US20180115286A1 true US20180115286A1 (en) | 2018-04-26 |
Family
ID=61951803
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US15/332,830 Active US9954495B1 (en) | 2016-10-24 | 2016-10-24 | PVT invariant peaking stage for continuous time linear equalizer |
Country Status (1)
Country | Link |
---|---|
US (1) | US9954495B1 (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10931249B2 (en) | 2018-06-12 | 2021-02-23 | Kandou Labs, S.A. | Amplifier with adjustable high-frequency gain using varactor diodes |
US10680634B1 (en) | 2019-04-08 | 2020-06-09 | Kandou Labs, S.A. | Dynamic integration time adjustment of a clocked data sampler using a static analog calibration circuit |
US10608849B1 (en) | 2019-04-08 | 2020-03-31 | Kandou Labs, S.A. | Variable gain amplifier and sampler offset calibration without clock recovery |
CN112100569B (en) * | 2020-08-24 | 2024-04-02 | 瑞声新能源发展(常州)有限公司科教城分公司 | Motor parameter tracking method, device, equipment and medium based on frequency domain analysis |
US11303484B1 (en) | 2021-04-02 | 2022-04-12 | Kandou Labs SA | Continuous time linear equalization and bandwidth adaptation using asynchronous sampling |
US11374800B1 (en) | 2021-04-14 | 2022-06-28 | Kandou Labs SA | Continuous time linear equalization and bandwidth adaptation using peak detector |
US11456708B1 (en) * | 2021-04-30 | 2022-09-27 | Kandou Labs SA | Reference generation circuit for maintaining temperature-tracked linearity in amplifier with adjustable high-frequency gain |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5283483A (en) | 1993-01-27 | 1994-02-01 | Micro Linear Corporation | Slimmer circuit technique |
WO1994017590A1 (en) | 1993-01-27 | 1994-08-04 | Micro Linear Corporation | Circuit technique that sets transconductance |
US5508570A (en) | 1993-01-27 | 1996-04-16 | Micro Linear Corporation | Differential amplifier based integrator having a left-half plane pole |
US6462623B1 (en) * | 1999-05-19 | 2002-10-08 | Parthus Ireland Limited | Method and apparatus for PLL with improved jitter performance |
CN101281057B (en) * | 2007-04-02 | 2011-06-22 | 鸿富锦精密工业(深圳)有限公司 | Airflow detecting device |
US7869494B2 (en) | 2007-10-03 | 2011-01-11 | Micron Technology, Inc. | Equalizer circuitry for mitigating pre-cursor and post-cursor intersymbol interference |
US7777526B2 (en) * | 2008-06-06 | 2010-08-17 | Altera Corporation | Increased sensitivity and reduced offset variation in high data rate HSSI receiver |
JP5502549B2 (en) * | 2010-03-26 | 2014-05-28 | ラピスセミコンダクタ株式会社 | Voltage output device |
US8405457B2 (en) * | 2010-06-15 | 2013-03-26 | Aeroflex Colorado Springs Inc. | Amplitude-stabilized odd order pre-distortion circuit |
US8964825B2 (en) | 2012-02-17 | 2015-02-24 | International Business Machines Corporation | Analog signal current integrators with tunable peaking function |
US8704583B2 (en) | 2012-02-17 | 2014-04-22 | International Business Machines Corporation | Capacitive level-shifting circuits and methods for adding DC offsets to output of current-integrating amplifier |
US8643432B1 (en) | 2012-07-27 | 2014-02-04 | Hong Kong Applied Science & Technology Research Institute Company Ltd. | Op-Amp sharing by swapping trans-conductance cells |
KR101563438B1 (en) * | 2014-12-11 | 2015-10-27 | 성균관대학교산학협력단 | Injection locked frequency divider capable of adjusting oscillation frequency |
US9425999B1 (en) | 2015-09-30 | 2016-08-23 | Synaptics Incorporated | Process-voltage-temperature (PVT) invariant continuous time equalizer |
-
2016
- 2016-10-24 US US15/332,830 patent/US9954495B1/en active Active
Also Published As
Publication number | Publication date |
---|---|
US9954495B1 (en) | 2018-04-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9954495B1 (en) | PVT invariant peaking stage for continuous time linear equalizer | |
US9602315B2 (en) | Method and apparatus for passive continuous-time linear equalization with continuous-time baseline wander correction | |
US8558611B2 (en) | Peaking amplifier with capacitively-coupled parallel input stages | |
CN105829988B (en) | Low noise low dropout regulator | |
US10193515B2 (en) | Continuous time linear equalizer with two adaptive zero frequency locations | |
US9794088B2 (en) | On-chip AC coupled receiver with real-time linear baseline-wander compensation | |
JP2015523040A (en) | Receiver with wide common mode input range | |
US6642791B1 (en) | Self-biased amplifier circuit and method for self-basing amplifier circuit | |
EP0664937A1 (en) | Line driver with adaptive output impedance | |
US10523470B1 (en) | Apparatus for performing baseline wander correction | |
US10284144B2 (en) | Amplifier circuit of high response speed and related clamping method | |
KR20170134420A (en) | Programmable high-speed equalizer and related method | |
US9887689B2 (en) | Pseudo resistance circuit and charge detection circuit | |
US10298426B2 (en) | Communication cable module and transmission loss compensation circuit | |
US8183921B1 (en) | Offset cancellation for continuous-time circuits | |
US20230268896A1 (en) | Continuous time linear equalization (ctle) feedback for tunable dc gain and mid-band correction | |
US10122337B2 (en) | Programmable gain amplifier | |
US20200021260A1 (en) | Amplification circuit, and receiving circuit, semiconductor apparatus and semiconductor system using the amplification circuit | |
WO2023018667A1 (en) | Variable gain amplifier with temperature compensated gain | |
EP3477863B1 (en) | Dynamic amplifying circuit | |
US20180292852A1 (en) | Temperature drift compensation | |
CN110311650B (en) | Low-pass filter circuit, low-pass filter and CMOS chip | |
US6469574B1 (en) | Selectable equalization system and method | |
TWI632781B (en) | Line receiver and driving method for line receiver | |
CN112671233B (en) | Compensation circuit and switching power supply |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SYNAPTICS INCORPORATED, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHEN, YONGGANG;KUMAR, SAGAR;SIGNING DATES FROM 20160923 TO 20160926;REEL/FRAME:040109/0989 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
AS | Assignment |
Owner name: WELLS FARGO BANK, NATIONAL ASSOCIATION, NORTH CAROLINA Free format text: SECURITY INTEREST;ASSIGNOR:SYNAPTICS INCORPROATED;REEL/FRAME:051316/0777 Effective date: 20170927 Owner name: WELLS FARGO BANK, NATIONAL ASSOCIATION, NORTH CARO Free format text: SECURITY INTEREST;ASSIGNOR:SYNAPTICS INCORPROATED;REEL/FRAME:051316/0777 Effective date: 20170927 |
|
AS | Assignment |
Owner name: WELLS FARGO BANK, NATIONAL ASSOCIATION, NORTH CAROLINA Free format text: CORRECTIVE ASSIGNMENT TO CORRECT THE CORRECT THE SPELLING OF THE ASSIGNOR NAME PREVIOUSLY RECORDED AT REEL: 051316 FRAME: 0777. ASSIGNOR(S) HEREBY CONFIRMS THE ASSIGNMENT;ASSIGNOR:SYNAPTICS INCORPORATED;REEL/FRAME:052186/0756 Effective date: 20170927 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |