US20090212864A1 - Preamplifier for receiver and method thereof - Google Patents
Preamplifier for receiver and method thereof Download PDFInfo
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- US20090212864A1 US20090212864A1 US12/071,485 US7148508A US2009212864A1 US 20090212864 A1 US20090212864 A1 US 20090212864A1 US 7148508 A US7148508 A US 7148508A US 2009212864 A1 US2009212864 A1 US 2009212864A1
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- 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
- H03F3/4521—Complementary long tailed pairs having parallel inputs and being supplied in parallel
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/30—Single-ended push-pull [SEPP] amplifiers; Phase-splitters therefor
- H03F3/3001—Single-ended push-pull [SEPP] amplifiers; Phase-splitters therefor with field-effect transistors
- H03F3/3022—CMOS common source output SEPP amplifiers
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- 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
- H03F3/45479—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection
- H03F3/45632—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection in differential amplifiers with FET transistors as the active amplifying circuit
- H03F3/45695—Differential amplifiers with semiconductor devices only characterised by the way of common mode signal rejection in differential amplifiers with FET transistors as the active amplifying circuit by using feedforward means
- H03F3/45699—Measuring at the input circuit of the differential amplifier
- H03F3/45704—Controlling the input circuit of the differential amplifier
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45008—Indexing scheme relating to differential amplifiers the addition of two signals being made by a resistor addition circuit for producing the common mode signal
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45074—A comparator circuit compares the common mode signal to a reference before controlling the differential amplifier or related stages
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45078—Indexing scheme relating to differential amplifiers the common mode signal being taken or deducted from the one or more inputs of the differential amplifier
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45586—Indexing scheme relating to differential amplifiers the IC comprising offset generating means
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45616—Indexing scheme relating to differential amplifiers the IC comprising more than one switch, which are not cross coupled
Definitions
- the invention relates in general to a preamplifier for a receiver and a method thereof, and more particularly to a preamplifier with wide range of the common voltage of the input differential voltage pair.
- FIG. 1 is a circuit diagram of a conventional rail-to-rail preamplifier for a receiver.
- the conventional rail-to-rail preamplifier 100 includes amplifiers 110 and 120 and an inverter 130 .
- the amplifiers 110 and 120 each amplify a differential voltage pair VN and VP and produce one voltage of the amplified differential voltage pair for the inverter 130 .
- the inverter 130 then pulls its output voltage Vo high or low based on these inputs.
- the transistors in amplifiers 110 and 120 are complementary, so that the preamplifier 100 is capable of amplifying the differential voltage VN and VP with wide common voltage range.
- the amplifiers 110 and 120 are powered by a high voltage supply power HVDD, which is for analog power, while the inverter 130 is powered by a low voltage supply power LVDD, which is for digital power.
- the high supply voltage HVDD is around 3.3V
- the low supply voltage LVDD is around 1.8V.
- the low supply voltage LVDD is even lower than the high supply voltage HVDD minus a threshold voltage of a transistor 121 in amplifier 120 .
- the transistor 131 in the inverter 130 is cut off, which causes the rail-to-rail preamplifier to become disabled.
- a preamplifier used in a receiver includes an input circuit, an output circuit.
- the input circuit receives an input differential voltage pair and pulls it down when the common voltage of the input differential voltage pair is higher than a reference voltage.
- the output circuit receives the input differential voltage pair outputted from the input circuit to pull high or low an output voltage accordingly.
- a preamplifier used in a receiver includes an input circuit and an amplifier.
- the input circuit receives an input differential voltage pair, pulls it down when the common voltage of the input differential voltage pair is higher than a reference voltage, and keeps it unchanged when the common voltage is not higher than the reference voltage.
- the amplifier includes a first stage amplifier and a second stage amplifier.
- the first stage amplifier powered by a high supply voltage, receives and amplifies the input differential voltage pair outputted from the input circuit to output an internal differential voltage pair.
- the second stage amplifier powered by a low supply voltage, receives and amplifies the internal differential voltage pair to pull high or low an output voltage.
- a method for preamplifying an input differential voltage pair, used in a receiver includes the following steps. Firstly, the input differential voltage pair is pulled down when the common voltage of the input differential voltage pair is higher than a reference voltage. Next, the input differential voltage pair is amplified to output an internal differential voltage pair. Then, the internal differential voltage pair is amplified to pull high or low a first output voltage.
- FIG. 1 is a circuit diagram of a conventional rail-to-rail preamplifier for a receiver.
- FIG. 2 shows a circuit diagram of the preamplifier according to a first embodiment of the invention.
- FIG. 3 shows a circuit diagram of the preamplifier according to a second embodiment of the invention.
- FIG. 2 shows a circuit diagram of the preamplifier 200 according to the first embodiment of the invention.
- the preamplifier 200 is for preamplifying an input differential voltage pair VIN and VIP to pull an output voltage Vo 1 for a receiver high or low.
- preamplifier 200 includes an input circuit 210 and an output circuit 220 .
- the input circuit 210 receives the input differential voltage pair VIN and VIP.
- the input circuit 210 pulls the input differential voltage pair VIN and VIP down to produce a differential voltage pair VIN′ and VIP′ and then transfers the differential voltage pair VIN′ and VIP′ to the output circuit 220 .
- the input circuit 210 When the common voltage Vcom of the input differential voltage pair VIN and VIP is not higher than the reference voltage Vr, the input circuit 210 directly transfers the input differential voltage pair VIN and VIP as the input differential voltage pair VIN′ and VIP′ to the output circuit 220 without pulling the input differential voltage pair VIN and VIP down.
- the output circuit 220 then takes the input differential voltage pair VIN′ and VIP′ and pulls the output voltage Vo 1 high or low.
- the input circuit 210 includes a comparator 230 and a level adjustment circuit 240 and switches 261 , 262 , 263 and 264 .
- the comparator 230 compares the common voltage Vcom of the input differential voltage pair VIN and VIP with the reference voltage Vr.
- the switches 261 to 264 are turned on or off based on the comparing result of the comparator 230 .
- the switches 263 and 264 are turned on to transmit the input differential voltage pair VIN and VIP to the level adjustment circuit 240 . Meanwhile, the switches 261 and 262 are turned off with the result that the input differential voltage pair will not be directly transmitted to the output circuit 220 .
- the level adjustment circuit 240 then pulls the input differential voltage pair VIN and VIP down. The pulled-down input differential voltage pair VIN and VIP is then transferred to the first stage amplifier 270 in the output circuit 220 .
- the level adjustment circuit 240 includes source followers 241 and 242 , which are for pulling down the voltages VIN and VIP, respectively, of the input differential voltage pair when the common voltage Vcom is higher than the reference voltage Vr.
- the source follower 241 includes transistors 243 and 244 . When the common voltage Vcom is higher than the reference voltage Vr, the gate of the transistor 243 receives the voltage VIP. The drain of the transistor 243 receives the high supply voltage HVDD and its source is connected to the drain of the transistor 244 . The transistor 244 has its source grounded.
- the transistor 243 When the transistor 243 receives the voltage VIP, the transistor 243 pulls down the voltage VIP by an amount equal to its gate-source cross voltage to produce the voltage VIP′ at its source which is connected to the output circuit 220 .
- the gate of the transistor 245 receives the voltage VIN. Then the transistor 245 pulls down the voltage VIN by an amount equal to its gate-source cross voltage to produce the voltage VIN′ at its source which is connected to the output circuit 220 .
- the switches 261 and 262 are turned on to transfer the voltages VIN and VIP to the output circuit 220 as the voltages VIN′ and VIP′, respectively,. Meanwhile, the switches 263 and 264 are turned off with the result that the level adjustment circuit 240 will not receive the input differential voltage pair VIN and VIP. Therefore, when the common voltage Vcom is not higher than the reference voltage Vr, the input differential voltage pair VIN and VIP is not pulled down but directly transferred to the output circuit 220 .
- the input circuit 210 further includes a voltage divider 250 to generate the common voltage Vcom of the input differential voltage pair VIN and VIP to the comparator 230 .
- the voltage divider 250 is a resistor string including resistors 251 and 252 which are serially connected. The voltage divider 250 is coupled between the voltage VIN and the voltage VIP to divide the voltage therebetween. In the first embodiment, the resistances of the resistors 251 and 252 are the same. Thus, the common voltage Vcom of the input differential voltage pair VIN and VIP is produced at the connection of the resistors 251 and 252 .
- the output circuit 220 is an amplifier.
- the output circuit 220 includes a first stage amplifier 270 and a second stage amplifier 280 .
- the first stage amplifier 270 is powered by the high supply voltage HVDD, which is for analog power
- the second stage amplifier 280 is powered by the low supply voltage LVDD, which is for digital power.
- the first stage amplifier 270 receives and amplifies the input differential voltage pair VIN′ and VIP′ produced by the input circuit 210 and produces an internal differential voltage pair Vin and Vip.
- the second stage amplifier 280 receives and amplifies the internal differential voltage pair Vin and Vip to pull the output voltage Vo 1 high or low.
- the first stage amplifier 270 includes transistors 271 , 272 , 273 .
- the transistor 271 is for receiving the high supply voltage HVDD and providing a bias current for the first stage amplifier 270 .
- the transistors 272 and 273 are for receiving the voltages VIN′ and VIP′, respectively.
- the source-drain cross voltage of the transistor 271 is Vsd.
- the source-gate cross voltage of the transistors 272 and 273 are Vsg.
- the second stage amplifier 280 includes transistors 281 , 282 , 283 , and 284 .
- the transistors 281 and 282 form a current mirror.
- the transistors 283 and 284 receive the voltage Vip and Vin, respectively.
- the output circuit 220 further includes an inverter 290 for amplifying the output voltage Vo 1 to produce an inverted output voltage Vo 2 .
- the amplifier 280 pulls the output voltage Vo 1 low, and the inverter 290 then pulls the output voltage Vo 2 high.
- the amplifier 280 pulls the output voltage Vo 1 high and the inverter 290 then pulls the output voltage Vo 2 low.
- the preamplifier 200 receives the input differential voltage pair VIN and VIP and pulls the output voltages Vo 1 and Vo 2 high or low according to the input differential voltage.
- the transistors 272 and 273 will be cut off, which causes the output circuit 220 to be disabled. Therefore, by applying the input circuit 210 , which pulls down the input differential voltage pair VIN and VIP when the common voltage Vcom of the input differential voltage pair VIN and VIP is too high, the transistors 272 and 273 are therefore enabled to receive the pulled-down input differential voltage VIN′ and VIP′ so as to be kept turned on.
- the reference voltage Vr is set to about HVDD/2, which ensures that the pulled down input differential voltage pair VIN′ and VIP′ are not to cut off to the transistors 272 and 273 .
- the input circuit 210 simply reproduces VIN and VIP as the differential voltage pair VIN′ and VIP′ at its output, in which case the transistors 272 and 273 will not be cut off.
- the preamplifier 200 is capable of properly preamplifying the input differential voltage pair even with wide range of common voltage.
- FIG. 3 shows a circuit diagram of the preamplifier 300 according to the second embodiment.
- the input circuit 310 pulls the input differential voltage pair DIN and DIP up to produce a differential voltage pair DIN′ and DIP′ and then transfers the differential voltage pair DIN′ and DIP′ to the output circuit 320 .
- the input circuit 310 when the common voltage Vcom′ is lower than the reference voltage Vr′, the switches 363 and 364 are turned on to transmit the input differential voltage pair DIN and DIP to the source followers 342 and 341 in the level adjustment circuit 340 , respectively. Meanwhile, the switches 361 and 362 are turned off. The transistors 346 and 344 in the source followers 342 and 341 then pulls the voltages DIN and DIP up, respectively, by amounts equal to the gate-drain cross voltages of the transistors 346 and 344 . The pulled-up input differential voltage pair DIN′ and DIP′ is then transferred to the first stage amplifier 370 in the output circuit 320 .
- the switches 361 and 362 are turned on to transmit the voltage DIN and DIP as the voltage DIN′ and DIP′ directly to the output circuit 320 . Meanwhile, the switches 363 and 364 are turned off, so that the level adjustment circuit 340 will not receive the input differential voltage pair DIN and DIP.
- the first and second stage amplifiers 370 and 380 are both powered by the same supply voltage, for example, one of the high and low supply voltages HVDD and LVDD.
- the functions of transistors 371 to 373 in the first stage amplifier 370 in FIG. 3 are similar to the function of the transistors 271 to 273 in the first stage amplifier 270 in FIG. 2 , respectively.
- the functions of the transistors 381 to 384 are similar to those of the transistors 281 to 284 , respectively.
- the corresponding transistors in the output circuits 320 and 220 are complementary.
- the transistor 371 is NMOS, while its corresponding transistor 271 is PMOS.
- the function of the inverter 390 is similar to that of the inverter 290 .
- the drain-source cross voltage of the transistor 371 is Vds
- the gate-source cross voltage of the transistors 372 and 373 are Vgs.
- the transistors 372 and 373 will be cut off, which causes the output circuit 320 to be disabled. Therefore, by applying the input circuit 310 , which pulls up the input differential voltage pair DIN and DIP when the common voltage Vcom′ of the input differential voltage pair DIN and DIP is too low, the transistors 372 and 373 therefore receive the pulled-up input differential voltage DIN′ and DIP′ so as to be kept turned on.
- the preamplifier 300 is capable of properly preamplifying the input differential voltage pair even with wide range of common voltage.
Abstract
Description
- 1. Field of the Invention
- The invention relates in general to a preamplifier for a receiver and a method thereof, and more particularly to a preamplifier with wide range of the common voltage of the input differential voltage pair.
- 2. Description of the Related Art
-
FIG. 1 is a circuit diagram of a conventional rail-to-rail preamplifier for a receiver. The conventional rail-to-rail preamplifier 100 includesamplifiers inverter 130. Theamplifiers inverter 130. Theinverter 130 then pulls its output voltage Vo high or low based on these inputs. The transistors inamplifiers preamplifier 100 is capable of amplifying the differential voltage VN and VP with wide common voltage range. - However, the
amplifiers inverter 130 is powered by a low voltage supply power LVDD, which is for digital power. The high supply voltage HVDD is around 3.3V, and the low supply voltage LVDD is around 1.8V. The low supply voltage LVDD is even lower than the high supply voltage HVDD minus a threshold voltage of atransistor 121 inamplifier 120. Thus, thetransistor 131 in theinverter 130 is cut off, which causes the rail-to-rail preamplifier to become disabled. - A preamplifier used in a receiver includes an input circuit, an output circuit. The input circuit receives an input differential voltage pair and pulls it down when the common voltage of the input differential voltage pair is higher than a reference voltage. The output circuit receives the input differential voltage pair outputted from the input circuit to pull high or low an output voltage accordingly.
- A preamplifier used in a receiver includes an input circuit and an amplifier. The input circuit receives an input differential voltage pair, pulls it down when the common voltage of the input differential voltage pair is higher than a reference voltage, and keeps it unchanged when the common voltage is not higher than the reference voltage. The amplifier includes a first stage amplifier and a second stage amplifier. The first stage amplifier, powered by a high supply voltage, receives and amplifies the input differential voltage pair outputted from the input circuit to output an internal differential voltage pair. The second stage amplifier, powered by a low supply voltage, receives and amplifies the internal differential voltage pair to pull high or low an output voltage.
- A method for preamplifying an input differential voltage pair, used in a receiver, includes the following steps. Firstly, the input differential voltage pair is pulled down when the common voltage of the input differential voltage pair is higher than a reference voltage. Next, the input differential voltage pair is amplified to output an internal differential voltage pair. Then, the internal differential voltage pair is amplified to pull high or low a first output voltage.
-
FIG. 1 is a circuit diagram of a conventional rail-to-rail preamplifier for a receiver. -
FIG. 2 shows a circuit diagram of the preamplifier according to a first embodiment of the invention. -
FIG. 3 shows a circuit diagram of the preamplifier according to a second embodiment of the invention. -
FIG. 2 shows a circuit diagram of thepreamplifier 200 according to the first embodiment of the invention. Thepreamplifier 200 is for preamplifying an input differential voltage pair VIN and VIP to pull an output voltage Vo1 for a receiver high or low. -
preamplifier 200 includes aninput circuit 210 and anoutput circuit 220. Theinput circuit 210 receives the input differential voltage pair VIN and VIP. In the first embodiment, when the common voltage Vcom of the input differential voltage pair VIN and VIP is higher than a reference voltage Vr, theinput circuit 210 pulls the input differential voltage pair VIN and VIP down to produce a differential voltage pair VIN′ and VIP′ and then transfers the differential voltage pair VIN′ and VIP′ to theoutput circuit 220. - When the common voltage Vcom of the input differential voltage pair VIN and VIP is not higher than the reference voltage Vr, the
input circuit 210 directly transfers the input differential voltage pair VIN and VIP as the input differential voltage pair VIN′ and VIP′ to theoutput circuit 220 without pulling the input differential voltage pair VIN and VIP down. Theoutput circuit 220 then takes the input differential voltage pair VIN′ and VIP′ and pulls the output voltage Vo1 high or low. - The
input circuit 210 is now described in detail. Theinput circuit 210 includes acomparator 230 and alevel adjustment circuit 240 andswitches comparator 230 compares the common voltage Vcom of the input differential voltage pair VIN and VIP with the reference voltage Vr. Theswitches 261 to 264 are turned on or off based on the comparing result of thecomparator 230. - When the common voltage Vcom is higher than the reference voltage Vr, the
switches level adjustment circuit 240. Meanwhile, theswitches output circuit 220. Thelevel adjustment circuit 240 then pulls the input differential voltage pair VIN and VIP down. The pulled-down input differential voltage pair VIN and VIP is then transferred to thefirst stage amplifier 270 in theoutput circuit 220. - In this embodiment, the
level adjustment circuit 240 includessource followers source follower 241 includestransistors transistor 243 receives the voltage VIP. The drain of thetransistor 243 receives the high supply voltage HVDD and its source is connected to the drain of thetransistor 244. Thetransistor 244 has its source grounded. - When the
transistor 243 receives the voltage VIP, thetransistor 243 pulls down the voltage VIP by an amount equal to its gate-source cross voltage to produce the voltage VIP′ at its source which is connected to theoutput circuit 220. - Similarly, when the common voltage Vcom is higher than the reference voltage Vr, the gate of the
transistor 245 receives the voltage VIN. Then thetransistor 245 pulls down the voltage VIN by an amount equal to its gate-source cross voltage to produce the voltage VIN′ at its source which is connected to theoutput circuit 220. - When the common voltage Vcom is not higher than the reference voltage Vr, the
switches output circuit 220 as the voltages VIN′ and VIP′, respectively,. Meanwhile, theswitches level adjustment circuit 240 will not receive the input differential voltage pair VIN and VIP. Therefore, when the common voltage Vcom is not higher than the reference voltage Vr, the input differential voltage pair VIN and VIP is not pulled down but directly transferred to theoutput circuit 220. - In this embodiment, the
input circuit 210 further includes avoltage divider 250 to generate the common voltage Vcom of the input differential voltage pair VIN and VIP to thecomparator 230. In the first embodiment, thevoltage divider 250 is a resistorstring including resistors voltage divider 250 is coupled between the voltage VIN and the voltage VIP to divide the voltage therebetween. In the first embodiment, the resistances of theresistors resistors - The
output circuit 220 is now described in detail. In the first embodiment, theoutput circuit 220 is an amplifier. Theoutput circuit 220 includes afirst stage amplifier 270 and asecond stage amplifier 280. In the first embodiment, thefirst stage amplifier 270 is powered by the high supply voltage HVDD, which is for analog power, while thesecond stage amplifier 280 is powered by the low supply voltage LVDD, which is for digital power. Thefirst stage amplifier 270 receives and amplifies the input differential voltage pair VIN′ and VIP′ produced by theinput circuit 210 and produces an internal differential voltage pair Vin and Vip. Thesecond stage amplifier 280 receives and amplifies the internal differential voltage pair Vin and Vip to pull the output voltage Vo1 high or low. - The
first stage amplifier 270 includestransistors transistor 271 is for receiving the high supply voltage HVDD and providing a bias current for thefirst stage amplifier 270. Thetransistors 272 and 273 are for receiving the voltages VIN′ and VIP′, respectively. The source-drain cross voltage of thetransistor 271 is Vsd. The source-gate cross voltage of thetransistors 272 and 273 are Vsg. - The
second stage amplifier 280 includestransistors transistors - In the first embodiment, the
output circuit 220 further includes an inverter 290 for amplifying the output voltage Vo1 to produce an inverted output voltage Vo2. - When the voltage VIP is higher than the voltage VIN, that is, the voltage VIP′ is higher than the voltage VIN′, the
amplifier 280 pulls the output voltage Vo1 low, and the inverter 290 then pulls the output voltage Vo2 high. When the voltage VIP is lower than the voltage VIN, that is, the voltage VIP′ is lower than the voltage VIN′, theamplifier 280 pulls the output voltage Vo1 high and the inverter 290 then pulls the output voltage Vo2 low. - Therefore, the
preamplifier 200 receives the input differential voltage pair VIN and VIP and pulls the output voltages Vo1 and Vo2 high or low according to the input differential voltage. - However, when the common voltage of the input differential voltage pair VIN′ and VIP′ is higher than the voltage HVDD-Vsd-Vsg, the
transistors 272 and 273 will be cut off, which causes theoutput circuit 220 to be disabled. Therefore, by applying theinput circuit 210, which pulls down the input differential voltage pair VIN and VIP when the common voltage Vcom of the input differential voltage pair VIN and VIP is too high, thetransistors 272 and 273 are therefore enabled to receive the pulled-down input differential voltage VIN′ and VIP′ so as to be kept turned on. - In the first embodiment, the reference voltage Vr is set to about HVDD/2, which ensures that the pulled down input differential voltage pair VIN′ and VIP′ are not to cut off to the
transistors 272 and 273. - Conversely, when the common voltage Vcom of the input differential voltage pair VIN and VIP is not higher than the reference voltage Vr, the
input circuit 210 simply reproduces VIN and VIP as the differential voltage pair VIN′ and VIP′ at its output, in which case thetransistors 272 and 273 will not be cut off. - Therefore, even if the common voltage Vcom of the input differential voltage pair VIN and VIP is high, the common voltage of the input differential voltage pair VIN′ and VIP′ produced by the
input circuit 210 will not be higher than the voltage HVDD-Vsd-Vsg, so that theoutput circuit 220 works properly. Thus, thepreamplifier 200 according to the first embodiment is capable of properly preamplifying the input differential voltage pair even with wide range of common voltage. -
FIG. 3 shows a circuit diagram of thepreamplifier 300 according to the second embodiment. In the second embodiment, when the common voltage Vcom′ of the input differential voltage pair DIN and DIP is lower than a reference voltage Vr′, theinput circuit 310 pulls the input differential voltage pair DIN and DIP up to produce a differential voltage pair DIN′ and DIP′ and then transfers the differential voltage pair DIN′ and DIP′ to theoutput circuit 320. - When the common voltage Vcom′ of the input differential voltage pair DIN and DIP is not lower than the reference voltage Vr′, the
input circuit 310 directly transfers the input differential voltage pair DIN and DIP as the input differential voltage pair DIN′ and DIP′ to theoutput circuit 320 without pulling the input differential voltage pair DIN′ and DIP′ up. Theoutput circuit 320 then takes the input differential voltage pair DIN′ and DIP′ and pulls the output voltage Vo1′ high or low. - The detailed description of the
input circuit 310 is explained as follows. In theinput circuit 310, when the common voltage Vcom′ is lower than the reference voltage Vr′, theswitches source followers level adjustment circuit 340, respectively. Meanwhile, theswitches transistors source followers transistors first stage amplifier 370 in theoutput circuit 320. - In the
input circuit 310, when the common voltage Vcom′ is not lower than the reference voltage Vr′, theswitches output circuit 320. Meanwhile, theswitches level adjustment circuit 340 will not receive the input differential voltage pair DIN and DIP. - In the
output circuit 320, the first andsecond stage amplifiers transistors 371 to 373 in thefirst stage amplifier 370 inFIG. 3 are similar to the function of thetransistors 271 to 273 in thefirst stage amplifier 270 inFIG. 2 , respectively. The functions of thetransistors 381 to 384 are similar to those of the transistors 281 to 284, respectively. The corresponding transistors in theoutput circuits transistor 371 is NMOS, while itscorresponding transistor 271 is PMOS. The function of the inverter 390 is similar to that of the inverter 290. - In the
output circuit 320, the drain-source cross voltage of thetransistor 371 is Vds, and the gate-source cross voltage of thetransistors 372 and 373 are Vgs. When the common voltage of the input differential voltage pair DIN′ and DIP′ is lower than the voltage equal to Vds+Vgs, thetransistors 372 and 373 will be cut off, which causes theoutput circuit 320 to be disabled. Therefore, by applying theinput circuit 310, which pulls up the input differential voltage pair DIN and DIP when the common voltage Vcom′ of the input differential voltage pair DIN and DIP is too low, thetransistors 372 and 373 therefore receive the pulled-up input differential voltage DIN′ and DIP′ so as to be kept turned on. - Consequently, even if the common voltage Vcom′ of the input differential voltage pair DIN and DIP is too low, the common voltage of the input differential voltage pair DIN′ and DIP′ produced by the
input circuit 310 will not be lower than the voltage Vds+Vgs, so that theoutput circuit 320 works properly. Thus, thepreamplifier 300 according to the second embodiment is capable of properly preamplifying the input differential voltage pair even with wide range of common voltage. - While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
Claims (19)
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US12/071,485 US7576609B1 (en) | 2008-02-21 | 2008-02-21 | Preamplifier for receiver and method thereof |
TW097112602A TWI410047B (en) | 2008-02-21 | 2008-04-08 | Preamplifier for receiver and method thereof |
CN2008101377387A CN101515789B (en) | 2008-02-21 | 2008-07-18 | Preamplifier for receiver and method thereof |
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US12/071,485 US7576609B1 (en) | 2008-02-21 | 2008-02-21 | Preamplifier for receiver and method thereof |
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US20110058635A1 (en) * | 2009-09-04 | 2011-03-10 | Ko Jae-Hong | Receiver for Receiving Signal Containing Clock Information and Data Information, and Clock-Embedded Interface Method |
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CN101741332A (en) * | 2009-12-10 | 2010-06-16 | 四川和芯微电子股份有限公司 | Low-resistance transmission line receiving preamplifier |
US9413568B2 (en) | 2013-09-27 | 2016-08-09 | Cavium, Inc. | Method and apparatus for calibrating an input interface |
US9087567B2 (en) | 2013-09-27 | 2015-07-21 | Cavium, Inc. | Method and apparatus for amplifier offset calibration |
US9496012B2 (en) * | 2013-09-27 | 2016-11-15 | Cavium, Inc. | Method and apparatus for reference voltage calibration in a single-ended receiver |
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JP4235433B2 (en) * | 2002-10-31 | 2009-03-11 | ザインエレクトロニクス株式会社 | Receiving circuit and differential circuit having the same |
CN100466033C (en) * | 2005-12-14 | 2009-03-04 | 奇景光电股份有限公司 | Outputting circuit, buffer circuit and voltage adjustment for source-level driver |
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- 2008-02-21 US US12/071,485 patent/US7576609B1/en not_active Expired - Fee Related
- 2008-04-08 TW TW097112602A patent/TWI410047B/en not_active IP Right Cessation
- 2008-07-18 CN CN2008101377387A patent/CN101515789B/en not_active Expired - Fee Related
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US4616189A (en) * | 1985-04-26 | 1986-10-07 | Triquint Semiconductor, Inc. | Gallium arsenide differential amplifier with closed loop bias stabilization |
US4904953A (en) * | 1988-04-22 | 1990-02-27 | Triquint Semiconductor, Inc. | Differential amplifier with common-mode bias feedback |
US7113017B2 (en) * | 2004-07-01 | 2006-09-26 | Intersil Americas Inc. | Floating gate analog voltage level shift circuit and method for producing a voltage reference that operates on a low supply voltage |
US7053712B2 (en) * | 2004-07-30 | 2006-05-30 | International Business Machines Corporation | Method and apparatus for controlling common-mode output voltage in fully differential amplifiers |
US7221190B2 (en) * | 2005-03-14 | 2007-05-22 | Texas Instruments Incorporated | Differential comparator with extended common mode voltage range |
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US20110058635A1 (en) * | 2009-09-04 | 2011-03-10 | Ko Jae-Hong | Receiver for Receiving Signal Containing Clock Information and Data Information, and Clock-Embedded Interface Method |
US8630373B2 (en) * | 2009-09-04 | 2014-01-14 | Samsung Electronics Co., Ltd. | Receiver for receiving signal containing clock information and data information, and clock-embedded interface method |
Also Published As
Publication number | Publication date |
---|---|
TW200937850A (en) | 2009-09-01 |
US7576609B1 (en) | 2009-08-18 |
CN101515789A (en) | 2009-08-26 |
CN101515789B (en) | 2011-03-16 |
TWI410047B (en) | 2013-09-21 |
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