JP2002529949A - Combined low power CFCMOS mixer and VCO reusing current - Google Patents

Abstract

(57) [Problem] To provide a mixer / oscillator device in which current consumption is reduced. An oscillating device based on MOS technology includes a self-controlled oscillator stage including oscillating means, cross-connected gate means, and output means. Further, the oscillating device includes a mixer device including a first stage and a second stage, each having a different combination of signal inputs, and connected to the output means of the oscillating device, and also including a mixer signal output mechanism. In particular, the output of the oscillator stage is connected via the current recycling path of the first stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention is a mixer / oscillator device including an oscillator having an oscillator supply terminal that generates a local oscillator signal and a mixer including a mixer supply terminal, wherein the local oscillator is connected to the mixer, The mixer further comprises a signal input for receiving a signal to be mixed with the local oscillator signal.

[0002] The invention also relates to an RF receiver circuit, and further to a portable communication device.

[0003]

[Prior art]

The first described device is already known from the dissertation sp23.7, read aloud in Session 23 of the ISSCC 97 and published on pages 390-391 of the meeting minutes.

[0004] Such circuits are often used in various portable telecommunications devices, such as telephones and pagers. In particular, the function of this circuit is generally to reduce the frequency of the input signal to a low value, even at DC.

[0005]

[Problems to be solved by the invention]

Generally, the current consumption of such a circuit is relatively high, as described in the specifications for low noise values of the constituent small devices. Due to the current drain indicated thereby, the battery life and / or the unique intervals between recharges all tend to remain too short.

[0006] It is therefore an object of the present invention, inter alia, to provide a device with reduced current consumption in the device described at the outset.

[0007]

[Means for Solving the Problems]

Thus, according to one aspect, the invention relates to the mixer / oscillator device described first, wherein the supply terminal of said oscillator is arranged to transmit a local oscillator signal current and a supply current, Is connected to the oscillator supply terminal and receives a supply current and a local oscillator current from the oscillator supply terminal.

[0008] By connecting the supply terminal of the oscillator to the supply terminal of the mixer, it is provided that the supply current of the oscillator also flows through the mixer. This eliminates the need for a separate supply current for the mixer. As a result, current consumption in the mixer / oscillator device is reduced.

According to one embodiment of the present invention, the oscillator supply terminal and the mixer supply terminal are connected via a main current path of a transistor having a control electrode connected to a reference voltage input. Features.

By connecting the oscillator supply terminal and the mixer supply terminal via a transistor whose control electrode is connected to a reference voltage input, the voltage applied to the oscillator supply terminal is independent of the operation of the mixer. Is obtained. This prevents undesirable effects such as a change in the local oscillator frequency due to the input RF signal.

According to another embodiment of the present invention, the oscillator includes another oscillator supply terminal for transmitting a local oscillator signal current and a supply current, and the mixer includes the other oscillator supply terminal. A second mixer supply terminal connected to the second oscillator terminal for receiving a supply current and a local oscillator current from the other oscillator supply terminal, and further comprising: a first mixer terminal and a second oscillator terminal. The oscillator signals are characterized by having opposite phases.

By using two oscillator supply terminals for transmitting local oscillator signals having opposite phases, it is obtained that the device draws a constant current from the power supply. This reduction in parasitic coupling is very important for RF circuits.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a conceptual diagram of a one-chip transceiver including a mixer and a VCO in an RF front-end unit 24. Such an arrangement is useful in low cost, wireless and battery powered transceiver environments, such as those available in cell phones, cordless phones, pagers, and other portable communication devices. In FIG. 1, the RF front end 22 + 24, the RF back end 26, and the baseband 28 subsystem are shown. The signal extracted by the antenna 20 is first amplified by the LNA circuit 22, and then down-converted in the block 24 together with one or more mixers MIX1. Block 19 is a bandpass filter, each having appropriate characteristics. The mixer function in question is to convert the input signal into an IF signal whose frequency has been reduced to a possibly zero value. In conventional mixer technology, a Gilbert cell is a VCO with one input port for the RF signal from the LNA and the other input port precisely tuned to the desired frequency, or a local oscillator. For signals from Depending on the function selected, the frequency of the LO may be higher (high-side injection), lower (low-side injection), or exactly equal to the frequency of the input RF. In general, the current consumption by both the VCO and the mixer is in the range of milliamps, as described in the VCO phase noise / spectral purity specification and the mixer stage noise figures, respectively. The present invention largely solves the disadvantages caused by these relatively large current values.

The circuitry of the present invention, which will be described in more detail below, forms part of a comprehensive circuit module 22. This circuit module 22 affects almost all of the required receiver functions of the portable communication device 36 and can be implemented as a single integrated circuit package. The communication device generally extracts the output signal from the baseband 28 in the processing stage 32 and further converts it into, for example, an audio signal or a control signal. Element 34 is a human interface module with keyboard, display, audio I / O and other possible functions. Element 30 is a transmission function module that receives a signal from processing module 32 and constructs a feasible transmission signal from this signal. This generally requires the reuse of various additional elements of the device, such as power supplies and antennas. For simplicity, these additional aspects are not detailed.

FIG. 2 shows a configuration of a general CMOS VCO. However, the present invention is not limited to this configuration. In this stand-alone circuit block,
The LCR oscillator circuit is connected via a resistor R to an appropriate power supply Vdd. Other fixed oscillator circuit configurations are also feasible. The cross-connected transistors M1 and M2 are connected to ground via a current source Iss, thereby providing an appropriate current value.

FIG. 3 shows a Gilbert cell mixer having a CMOS configuration. However, the present invention is not limited to this configuration. In this stand-alone circuit block, the mixer circuit is connected to an appropriate power supply Vdd via an impedance Z. The first input mixer stage comprises a pair of transistors M7 and M8. These transistors M7, M8 are controlled by a first complementary input signal RF / VCO and connected to ground via a current source Iss, thereby being further controlled by a second input mixer stage, Transmission with an appropriate current value becomes possible. This second input mixer stage comprises four transistors M3, M4, M5, M6 in pairs,
Each pair is arranged in series with one of the first stage transistors, and each pair is controlled by a second complementary input signal VCO / RF. According to this embodiment, the terminal MXo
The output signal value at ut represents the result of mixing the two input signals. Now, a technique according to the present invention for saving power is to reuse current, which has proved to be very effective. For a more detailed description, reference is first made to FIG. FIG. 4 is a schematic diagram of the combination of FIG. 2 and FIG. 3, in which the bold line indicates the main current flow. The arrows connected to the west and east sides of the mixer stage MX indicate the direction of the input signal and the direction of the output signal, respectively. In addition, 2
There are clearly two current paths, IMX and IVCO, respectively, which flow parallel current from the power supply to ground and are individually adapted to each one of the two component circuits VCO and MX. A diagram according to the invention is now shown in FIG. 7, which is a schematic diagram of FIG.
Here, the current shown again by the thick line flows first through the mixer MX and then through the oscillator VCO before reaching the ground terminal. As a result, the power supply current is reused. If equal current values are actually required for both of these component circuits, then by properly stacking these two circuits and designing them appropriately from each other's perspective, the total power savings will be 50% Will be. For example, if one of the two elements MX, VCO can actually be driven with less current than the other, the current savings can actually be less than 50%.

FIG. 5 shows a VCO realized by the present invention, realized by nMOS transistors.
-Indicates the configuration of MX. Alone, it can also be realized by other MOS type configurations. Now, the transistors M1, M2, in positive feedback, form a negative small signal resistance, guaranteeing the initial start-up of the oscillator and subsequently providing a large signal amplitude adjustment. The frequency of the oscillator is tunable by a varactor. Transistors M3, M4, M5 and M6, together with transistors M1, M2, M7 and M8, again form the double balanced Gilbert cell stage of FIG. Transistor M
1, M2, M7, and M8 simultaneously constitute an LO oscillator. The oscillator and Gilbert cell are integrated in an inventive manner.

The RF signal is supplied separately to the transistors M3 to M6. The outputs of the transistors M3 to M6 are cross-connected as in FIG. The oscillator is connected to the mixer via transistors M7 and M8. Therefore, the transistor M7
Is connected to the supply terminal of the oscillator, and the drain of the transistor M7 is connected to the supply terminal of the mixer. The source of transistor M8 is connected to the supply terminal of an additional oscillator, and the drain of transistor M8 is connected to the supply terminal of an additional mixer.

A particular function of the transistors M7, M8, which are appropriately biased by the voltage Vbias, is to provide the necessary isolation between the VCO part and the top of the mixer circuit. The network Z is capable of selecting a frequency.

The oscillator is voltage controlled through a varactor tuning circuit, as shown in FIG. In particular, note the characters A and B that match between FIG. 5 and FIG. On the other hand, other elements in FIG. 5 are omitted for clarity. Because the control signal is a DC voltage, a resistor is needed to provide the required isolation. On the other hand, the control voltage to the varactor must not create a forward bias for the varactor and affect the operating points of nodes A and B. This requires two series capacitors in the coil. Therefore, the frequency of the oscillator is determined by all elements,
Tuning can be performed via the control voltage Vc. To extend the tuning range of the oscillator and compensate for process variations, temperature changes, aging, etc., a binary-weighted capacitor array may be added. Such a capacitor array will not be described in detail for simplicity. As a result, the illustrated circuit includes resistors 44, 4 in combination with a branched varactor 40 interconnected to ground.
6, a series connection of the capacitor 40 and the oscillator circuit section L.

In addition to power savings, the sum of the two connection pads can be saved compared to current stand-alone solutions. The total number of transistors is also reduced to almost the number of Gilbert mixers alone, thereby saving silicon area. Computer testing gave the following results: 930MHz with peak value of 1mV
With a sinusoidal input of, the oscillator frequency of the integrated oscillator was 879.5 MHz with low side injection. The resulting output IF is 50.5
MHz. The oscillator stabilized three microsects after applying the supply voltage. The LC resonance network had L = 10 nH and C = 2.78 pF and Q = 60. The achieved mixer gain was 6 dB. An additional parameter is Vdd
= 2V, power consumption 200 microamps, and minimum gate width 0.35 micron CO75 CMOS process.

[0022]

【The invention's effect】

 As described in detail above, the present invention has the following effects.

That is, according to the present invention, since the supply terminal of the oscillator and the supply terminal of the mixer are connected, the supply current of the oscillator also flows through the mixer, and a separate current is supplied to the mixer. Eliminates the need. As a result, a mixer / oscillator device with greatly reduced current consumption is provided.

Further, according to the present invention, since an RF front-end module based on the above-described mixer / oscillator device is provided, an RF receiver circuit module with significantly reduced current consumption is provided.

Further, according to the present invention, there is provided a portable communication device having the above-mentioned RF receiver circuit module, so that current consumption is significantly reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a one-chip transceiver including a mixer and a VCO in a front end unit.

FIG. 2 is a configuration diagram of a CMOS VCO.

FIG. 3 is a diagram illustrating a Gilbert cell mixer.

FIG. 4 is a schematic view of a combination of FIG. 1 and FIG. 2;

FIG. 5 is a configuration diagram of VCOMX that can be realized by the present invention.

FIG. 6 illustrates a varactor tuning circuit.

FIG. 7 is a schematic diagram of FIG.

[Explanation of symbols]

 Reference Signs List 19 band-pass filter 22 LNA circuit 24 RF front-end unit 26 RF back-end 28 baseband 30 transmission function module 34 human interface module 36 portable communication device 40 capacitor 42 varactor 44, 46 resistance A, B node IMX, IVCO Current path L Oscillator circuit section M1 to M8 Transistor MIX1 Mixer MX Mixer stage

──────────────────────────────────────────────────の Continuation of front page (71) Applicant Groenewoodseweg 1, 5621 BA Eindhoven, The Netherlands

Claims (8)

[Claims] An oscillator having a local oscillator signal and having an oscillator supply terminal; and a mixer having a mixer supply terminal, wherein the local oscillator is connected to the mixer, and the mixer includes: A signal input for receiving a signal to be mixed with the local oscillator signal, wherein a supply terminal of the oscillator is arranged to transmit a local oscillator signal current and a supply current; A mixer / oscillator device connected to the oscillator supply terminal and receiving a supply current and a local oscillator current from the oscillator supply terminal. 2. The device according to claim 1, wherein the oscillator supply terminal and the mixer supply terminal are connected via a main current path of a transistor having a control electrode connected to a reference voltage input. apparatus. 3. The oscillator further comprises another oscillator supply terminal for transmitting a local oscillator signal current and a supply current, and a mixer connected to the other oscillator supply terminal for supplying the supply current and the local oscillator. 3. Apparatus according to claim 1 or 2, further comprising another mixer supply terminal receiving current from the other oscillator supply terminal. 4. The apparatus according to claim 1, wherein the mixer device comprises a Gilbert cell. 5. The oscillator includes a differential transistor pair including a first transistor and a second transistor, wherein a first main electrode of the first transistor and a first main electrode of the second transistor are provided. Is connected to a current source, the second main electrode of the first transistor is connected to the first oscillator supply terminal, and the second main electrode of the second transistor is connected to the second Connected to an oscillator supply terminal, the second main electrode of the first transistor is connected to a control electrode of the second transistor, and the second main electrode of the second transistor is connected to the first transistor. 4. The device according to claim 3, wherein the device is connected to a control electrode of the transistor. 6. The oscillator according to claim 1, further comprising a frequency determining element connected between the second main terminal of the first transistor and the second main electrode of the second transistor. 7. The apparatus of claim 6, wherein 7. An RF receiver circuit module comprising an RF front-end module based on the device according to claim 1, wherein the output of the mixer is connected to the input of a cascade connection of an IF module and a baseband module. 8. A portable communication device comprising the receiver circuit module according to claim 7, interconnected with signal processing means, and further comprising human interface means and signal transmission means interconnected with the signal processing means. .