Cascaded low-noise wideband active phase shifters.

Abstract

The apparatus and associated method relate to a low-noise wideband active phase shifter. The low-noise wideband active phase shifter includes first and second transconductance cells, a fixed LC series network, and a tunable LC series network configured to form an all-pass lattice network. The first and second transconductance cells each include a transistor, a feedback network, and a transistor bias network. The transistor has an input terminal and an output terminal. The negative feedback network electrically couples the input terminal and the output terminal of the transistor. The bias network provides an input bias and an output bias for the transistor. The fixed LC series network is connected between the first transconductance cell and the second transconductance cell. The tunable LC series network is connected between the first transconductance cell and the second transconductance cell.

Description

[Background technology]

[0001] Modern RADAR and wireless communications often rely on electrical phase steering of antenna patterns. Such phase steering is performed by exciting different antennas in an array with electronic signals that have specific phase relationships to one another. These phase relationships (e.g., signals of a common frequency but with different delay relationships to one another) are produced by shifting the phase of these electronic signals by different angular amounts. Coordination of the relative phase with the geometric positions of the antennas produces electromagnetic waves that are specifically directed. Precise control of the relative phase of these signals results in precise control of the beam direction. As the desired bandwidth and frequency of operation increase, precision such as these becomes increasingly difficult to achieve.

[0002] Traditionally, phase shifting has been implemented in a variety of ways. For example, switched-line phase control simply switches between different lengths (and therefore time delays) between different transmission lines. Switching the ends of a transmission line creates differences in reflections, resulting in a phase change in the sum of the incident and reflected waves. Switching the load of a transmission line changes the impedance characteristics of such a line, thus changing the signal propagation speed and causing a phase change at the output of such a transmission line. Phase changes of the signal also occur when high-pass and / or low-pass filters are used. All of these traditional phase shifting methods are essentially passive (except for the use of switches), and therefore incur losses as the signal passes through them. Furthermore, some traditional phase shifting techniques, e.g. high-pass and / or low-pass filtering, have a narrow bandwidth over which a constant phase shift occurs. Summary of the Invention

[0003] The apparatus and associated method relate to a low-noise wideband active phase shifter including first and second transconductance cells, a fixed LC series network, and a tunable LC series network. Each of the first and second transconductance cells includes a transistor, a feedback network, and input and output biasing networks. The transistor has an input terminal and an output terminal. The feedback network electrically couples the input terminal and the output terminal of the transistor. The input biasing network and the output biasing network respectively input bias and output bias the transistor. The fixed LC series network is connected between the first transconductance cell and the second transconductance cell. The tunable LC series network is connected between the first transconductance cell and the second transconductance cell. The fixed LC series network and the tunable LC series network form an all-pass lattice network together with the first and second transconductance cells.

[0004] Some embodiments relate to a cascaded low noise wideband phase shifter including a plurality of cascaded low noise wideband active phase shift stages. Each low noise wideband active phase shift stage includes a first and a second transconductance cell. Each of the first and second transconductance cells includes a transistor, a feedback network, and input and output biasing networks. The transistor has an input terminal and an output terminal. The feedback network electrically couples the input terminal and the output terminal of the transistor. The input biasing network and the output biasing network input and output bias the transistor, respectively. A fixed LC series network is connected between the first transconductance cell and the second transconductance cell. A tunable LC series network is connected between the first transconductance cell and the second transconductance cell. The fixed LC series network and the tunable LC series network form an all-pass lattice network together with the first and second transconductance cells. [Brief description of the drawings]

[0005] [Figure 1]FIG. 1 is a block diagram of a three-stage wideband active phase shifter with 360 degree control. [Diagram 2] FIG. 2 is a schematic diagram of a single stage of a wideband active phase shifter. [Diagram 3] 1 is a circuit layout of a single stage of a wideband active phase shifter. [Figure 4] 4 is a graph of relative phase as a function of frequency using various values ​​of feedback capacitance in the wideband active phase shifter of FIGS. 2 and 3; [Diagram 5] 4A-4D are graphs of S-parameter / frequency and noise figure / frequency using various values ​​of feedback capacitance for the wideband active phase shifter of FIGS. 2 and 3. [Figure 6] 4 is a graph of linear phase as a function of frequency using various values ​​of feedback capacitance for the two cascaded wideband active phase shifters of FIGS. 2 and 3. FIG. [Figure 7] 1A and 1B show gain and phase diagrams for various combinations of feedback capacitances of the three wideband active phase shifters of FIGS. 2 and 3 cascaded as shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] The apparatus and associated method relate to a low-noise wideband active phase shifter. The low-noise wideband active phase shifter includes first and second transconductance cells configured to form an all-pass lattice network, a fixed LC series network, and a tunable LC series network. The first and second transconductance cells each include a transistor, a feedback network, and a transistor bias network. The transistor has an input terminal and an output terminal. The negative feedback network electrically couples the input terminal and the output terminal of the transistor. The bias network input biases and output biases the transistor. The fixed LC series network is connected between the first transconductance cell and the second transconductance cell. The tunable LC series network is connected between the first transconductance cell and the second transconductance cell.

[0007] FIG. 1 is a block diagram of a three-stage configuration of a wideband active phase shifter with 360 degrees of control. In FIG. 1, the cascaded low-noise wideband phase shifter 10 includes a first stage phase shifter 12A, a second stage phase shifter 12B, and a third stage phase shifter 12C connected in a cascaded manner (i.e., in a series manner). Each of the first stage, second stage, and third stage phase shifters 12A, 12B, and 12C contributes to the performance of the cascaded low-noise wideband phase shifter 10. The total phase shift resulting from a signal passing through the cascaded low-noise wideband phase shifter 10 is the sum of the phase shift resulting from a signal passing through each of the first stage, second stage, and third stage phase shifters 12A, 12B, and 12C. As shown in FIG. 1, the first stage phase shifter 12A provides coarse adjustment of phase shifts of 0 degrees, 45 degrees, 90 degrees, and 135 degrees. The second stage phase shifter 12B provides fine adjustment between 0 and 45 degrees in 4 degree intervals. Thus, after a signal passes through both the first and second stage phase shifters 12A and 12B, the resulting signal can be phase shifted between 0 and 180 degrees with a resolution of 4 degrees. The third stage phase shifter 12C provides an additional phase shift of either 0 or 180 degrees. Thus, after a signal passes through the first, second, and third stage phase shifters 12A, 12B, and 12C, the resulting signal can be phase shifted between 0 and 360 degrees with a resolution of 4 degrees.

[0008] The noise factor F of the cascaded low noise wideband phase shifter 10 is given by:

number

[0009] The frequency response of the cascaded low noise wideband phase shifter 10 is the product of the frequency responses of the first, second and third stage phase shifters 12A, 12B and 12C. Therefore, to obtain a wideband frequency response, each of the first, second and third stage phase shifters 12A, 12B and 12C must have a wideband frequency response. Such a wideband frequency response for phase shifters, such as the first, second and third stage phase shifters 12A, 12B and 12C, means that the phase shift of signals passing through these phase shifters is substantially constant over a wide band of frequencies.

[0010] FIG2 is a schematic diagram of a single stage of a wideband active phase shifter. In FIG2, the low-noise wideband active phase shifter 12 includes first and second stage transconductance cells 14 and 16, respectively, and fixed and adjustable LC series networks 18 and 20, respectively. The first and second stage transconductance cells 14 and 16, respectively, and the fixed and adjustable LC series networks 18 and 20 are interconnected to form an all-pass lattice network. The low-noise wideband active phase shifter 12 forms an impedance bridge with the fixed and adjustable LC series networks 18 and 20, respectively, connected between the first stage transconductance cell 14 and the second stage transconductance cell 16. The fixed LC network 18 includes inductors 18L1 and 18L2, a resistor 18R, and a capacitor 18C. The tunable LC series network 20 is tunable by selection of one or more series capacitor pairs 20C1-20C4 via select transistors 20T1-20T4.

[0011] In the illustrated embodiment, each of the first and second stage transconductance cells 14 and 16 includes a transistor 14T and 16T, respectively. The transistors 14T and 16T are high frequency FETs or BJTs, such as high carrier mobility FETs or BJTs (e.g., using GaAs, GaN, SiGe, etc.). In the illustrated embodiment, the transistors 14T and 16T are field effect transistors (FETs) configured in a common source configuration. The first stage transconductance cell 14 has a gate input terminal, a source terminal directly connected to ground, and a drain output terminal. The second stage transconductance cell 16 includes a gate input terminal, a transmission line 16TL, and a resistor 16R. S The input has a source terminal connected to ground via a drain output terminal.

[0012] Each of the first and second stage transconductance cells 14 and 16 has an RC parallel feedback path 14FB and 16FB, respectively. RB is a capacitor 14C connected to the gate of the FET 14T and the drain of the FET 14T. RB In a similar manner, resistor 16R of RC parallel feedback path 16FB is connected between FB is the gate of FET 16T and the capacitor 16C, which is also connected to the drain of FET 16T. FB Feedback paths 14FB and 16FB provide negative feedback to flatten the gain / frequency curves and broaden the phase and amplitude responses of the first and second stage transconductance cells 14 and 16, respectively.

[0013] Additionally, feedback paths 14FB and 16FB are used to inject bias into the first and second stage transconductance cells 14 and 16, respectively. The gate bias (e.g., input bias) of the first stage transconductance cell 14 is fed to the resistor 14R in the feedback path 14FB. FB and capacitor 14C FBThe gate bias of the second-stage transconductance cell 16 is injected into the series connection point of the resistor 16R RB and capacitor 16C FB The resistor 14R FB and 16R FB are large value resistors to provide isolation between any applied bias (e.g., voltage bias) and the gate nodes of FETs 14T and 16T, respectively. The first and second stage transconductance cells are biased such that the low noise wideband active phase shifter 12 has a gain greater than unity from input to output. Such gains allow the input referred noise of the subsequent stages of low noise wideband active phase shifters 12B and 12C to be reduced by the gain of the first stage low noise wideband active phase shifter 12A. Similarly, the gain of the second stage low noise wideband active phase shifter 12B further reduces the input referred noise of the third stage low noise wideband active phase shifter 12C.

[0014] The first and second stage transconductance cells 14 and 16 are mutually coupled via both fixed and adjustable LC series networks 18 and 20. The fixed LC series network 16 includes an inductor 18L1, a resistor 18R, an inductor 18L2, and a capacitor 18C connected in series between the output of the first stage transconductance cell 14 (i.e., the drain of transistor 14T) and the input of the second stage transconductance cell 16 (i.e., the gate of transistor 16T). The drain bias of the first stage transconductance cell 14 is implemented using the fixed LC series network 18. The drain bias of the first stage transconductance cell 14 is injected into the node connecting the inductor 18L1 of the fixed LC series network 18 with the resistor 18R. The first stage drain bias network 14N BIAS is resistor 14R BIAS and 14C BIAS Includes resistor 14R BIAS is the bias injection point of the fixed LC series network 16 mentioned above, and the resistor 14R BIAS and a capacitor 14C extending between BIASThe drain bias of the second stage transconductance cell 16 is coupled between the drain bias network 16N BIAS The drain bias network is implemented using a 16R resistor. BIAS , Capacitor 16C1 BIAS , 16C2 BIAS , and 16C3 BIAS , and inductor 16L BIAS Includes.

[0015] The tunable LC series network 20 shares the inductor 16L with the fixed LC series network, and further includes a tuning capacitor pair 20C1-20C4 extending between the output of the first stage transconductance cell 14 (via the inductor 18L1 of the fixed LC network 18) and the source of the transistor 16T (via the transmission line 16TL). The tuning capacitor pair 20C1-20C4 provides tuning for the tunable LC series network 20. Tuning is achieved by selection of the tuning capacitor pair 20C1-20C4 via the selection transistors 20T1-20T4. Each embodiment of the low noise wideband active phase shifters 12A, 12B, and 12C uses different capacitance values ​​for the tuning capacitor pair 20C1-20C4 to provide different amounts of precision and dynamic range of the generated phase shift tuning. As mentioned above, in one embodiment, the first stage provides a relatively coarse phase adjustment in 45 degree steps, the second stage provides fine adjustment in 4 degree steps, and the third stage provides 0 or 180 degree adjustment. The resulting dynamic range of three such cascaded low noise wideband active phase shifters 12A, 12B, and 12C can provide a full 360 degree phase adjustment in 4 degree steps.

[0016] In addition to the all-pass lattice network described above, the low noise wideband active phase shifter 12 includes an input passive network 22 and an output passive network 24. The input passive network 22 includes transmission lines 22TL1 and 22TL2, capacitors 22C1 and 22C2 that couple the transmission lines 22TL1 and 22TL2 to ground GND, and a series capacitor 22C3 through which the input signal is AC-coupled to the input of the first stage transconductance cell 14. The output passive network 24 includes a transmission line 24TL, capacitors 24C1 and 24C2, and an AC coupling capacitor 24C3.

[0017] FIG. 3 is a circuit layout of a single stage of a wideband active phase shifter. In FIG. 3, the low noise wideband active phase shifter 12 includes various input and output pad connections, including an RF input pad, an RF output pad, a gate bias pad VG1 and a drain bias pad VD1 for the first stage transconductance cell 14, a gate bias pad VG2 and a drain bias pad VD2 for the first stage transconductance cell 16, tuning capacitor selection pads VSW1-4, and a ground pad GND. In FIG. 3, each of the components described above with reference to FIG. 2 is depicted as seen from a top view of an embodiment of a circuit board assembly. The first and second stage transconductance cells 14 and 16 are disposed between the RF input pad and the RF output pad. Note that the transmission line 24TL of the output network 24 has impedance controlled by a ground strip running alongside the transmission line 24TL.

[0018] FIG. 4 is a graph of relative phase as a function of frequency using various values ​​of feedback capacitance in the wideband active phase shifter of FIGS. 2 and 3. In FIG. 4, graph 26 includes a horizontal axis 28, a vertical axis 30, and phase / frequency relationships 32A-32J. Horizontal axis 28 indicates the frequency of the signal input to the RF input pad / port of low noise wideband active phase shifter 12. Vertical axis 30 indicates the relative phase shift of the signal at the RF output pad / port of low noise wideband active phase shifter 12. Phase / frequency relationships 32A-32J indicate the relationship between the relative phase and frequency of the waveform phase shifted by low noise wideband active phase shifter 12 using various values ​​of tuning capacitance. These various values ​​of tuning capacitance are obtained by selecting various combinations of tuning capacitor pairs 20C1-20C4. In graph 26, phase / frequency relationships 32A-32J correspond to tuning capacitance values ​​of 0.100, 0.120, 0.220, 0.320, 0.420, 0.520, 0.620, 0.720, 0.820, and 0.920 pF. As shown in graph 26, each of phase-frequency relationships 32A-32J is constant within some range of its nominal value over a wide frequency span. In some embodiments, each of phase / frequency relationships 32A-32J is within ±5, 10, or 15 percent of its nominal value over an octave, two octaves, or even ten or more frequency bands. Flat frequency responses such as these can be obtained at high frequencies, such as 30, 50, or even 80 GHz.

[0019] 5A-5D are graphs of S-parameter / frequency and noise figure / frequency relationships using various values ​​of feedback capacitance for the wideband active phase shifter of FIGS. 2 and 3. In FIGS. 5A-5D, graphs 34A-34D show S-parameter / frequency relationships for forward transmission, input return loss, output return loss, and noise figure / frequency relationships, respectively. In graphs 34A-34D, horizontal axes 36A-36D each show frequency. In graph 34A, vertical axis 38A shows forward transmission measured in decibels dB. In graph 34A, a series of forward transmission / frequency relationships are illustrated. These forward transmission / frequency relationships correspond to various values ​​of tuning capacitance selected by various combinations of tuning capacitor pairs 20C1-20C4. As shown by these forward transmission / frequency relationships, the low noise wideband active phase shifter 12 provides gain over a wide frequency band and provides a nearly constant phase shift of a signal input thereto.

[0020] In graph 34B, vertical axis 38B represents input return loss measured in decibels dB. In graph 34B, a series of input return loss / frequency relationships are illustrated. These input return loss / frequency relationships correspond to various values ​​of tuning capacitance selected by various combinations of tuning capacitor pairs 20C1-20C4. As illustrated by these input return loss / frequency relationships, the return loss of a signal input to low noise wideband active phase shifter 12 is relatively modest over a bandwidth of frequencies over which low noise wideband active phase shifter 12 provides a nearly constant phase shift of a signal input thereto.

[0021] In graph 34C, vertical axis 38C also shows output return loss measured in decibels dB. In graph 34C, a series of output return loss / frequency relationships are illustrated. These output return loss / frequency relationships correspond to various values ​​of tuning capacitance selected by various combinations of tuning capacitor pairs 20C1-20C4. As shown by these return loss / frequency relationships, the return loss of a signal input to low noise wideband active phase shifter 12 is relatively modest over the bandwidth of frequencies over which low noise wideband active phase shifter 12 provides a nearly constant phase shift of a signal input thereto.

[0022] In graph 34D, vertical axis 38D represents noise figure measured in decibels dB. In graph 34D, a series of noise figure / frequency relationships are illustrated. These noise figure / frequency relationships correspond to various values ​​of tuning capacitance selected by various combinations of tuning capacitor pairs 20C1-20C4. As illustrated by these noise figure / frequency relationships, the noise figure is relatively modest over a bandwidth of frequencies over which low noise wideband active phase shifter 12 provides a nearly constant phase shift of signals input thereto.

[0023] FIG. 6 is a graph of linear phase as a function of frequency using various values ​​of feedback capacitance for two cascaded wideband active phase shifters of FIG. 2 and FIG. 3. In FIG. 6, graph 36 includes a horizontal axis 38, a vertical axis 40, and a phase variation / frequency relationship 42. Horizontal axis 38 indicates frequency, and vertical axis indicates phase. Each of the phase variation / frequency relationships 42 represents the linear phase of the signal at the output of two cascaded stages of low noise wideband active phase shifter 12 (e.g., the first and second stages of low noise wideband active phase shifters 12A and 12B). The phase variation / frequency relationships 42 correspond to various values ​​of tuning capacitance selected by various combinations of tuning capacitor pairs 20C1-20C4 for each of the two stages 12A and 12B. As can be seen, the first stage low noise wideband active phase shifter 12A provides a large phase step, and the second stage low noise wideband active phase shifter 12A provides small phase steps that form groups within each of the large phase steps. Such a graph shows that by cascading low noise wideband active phase shifters 12, both coarse and fine phase shift control can be achieved.

[0024] 7A and 7B are diagrams illustrating gain and phase for various combinations of feedback capacitances of the three wideband active phase shifters of FIGS. 2 and 3 cascaded as shown in FIG. 1. In FIG. 7, a polar diagram 44 is shown illustrating a series of gain / phase data points P N (r,θ) around each gain / phase data point P N (r,θ) corresponds to a unique selection of tuning capacitances selected for use in the three stages of the cascaded low noise wideband phase shifter 10. As shown in polar diagram 44, the span of phase that can be obtained from such a span of selected tuning capacitances is a full 360 degrees. Furthermore, the gains of each of these phase shifted signals (gain / phase data points P N (r,θ) from the origin) is within a small fraction of the nominal gain value. N The gain distribution of (r,θ) is the gain / phase data points PN Within ±10, 15, 20, or 30% of the nominal or average gain of (r,θ).

[0025] 7B, graph 46 illustrates the same data shown in graph 42, but in a phase / frequency relationship manner. Graph 44 has a horizontal axis 48, a vertical axis 50, and a phase frequency relationship θ N (f) Phase-frequency relationship θ N Each of (f) corresponds to a unique selection of tuning capacitances selected for use in the three stages of the cascaded low noise wideband phase shifter 10. As shown in graph 46, the phase frequency relationship θ N (f) is substantially constant not only over the entire 360 ​​degree phase span, but also over a large frequency bandwidth. Furthermore, the phase-frequency relationship θ N (f) is the phase-frequency relationship θ over a large frequency bandwidth that is substantially constant N (f) has another phase-frequency relationship θ N (f) (e.g., going from a state exhibiting a phase shift smaller than another to a state exhibiting a phase larger than the others). Such well-behaved phase-frequency relationships allow operation over a large frequency bandwidth while maintaining phase relationships with other signals that are differently phase shifted. Such well-behaved signals can be used, for example, in phased array antennas to perform multi-beam transmissions in separate and different directions.

[0026] Discussion of possible embodiments The following is a non-exclusive description of possible embodiments of the present invention.

[0027] The apparatus and associated method relate to a low-noise wideband active phase shifter including first and second transconductance cells, a fixed LC series network, and a tunable LC series network. Each of the first and second transconductance cells includes a transistor, a feedback network, and input and output biasing networks. The transistor has an input terminal and an output terminal. The feedback network electrically couples the input terminal and the output terminal of the transistor. The input biasing network and the output biasing network respectively input bias and output bias the transistor. The fixed LC series network is connected between the first transconductance cell and the second transconductance cell. The tunable LC series network is connected between the first transconductance cell and the second transconductance cell. The fixed LC series network and the tunable LC series network form an all-pass lattice network together with the first and second transconductance cells.

[0028] The system of the preceding paragraph may optionally and / or alternatively include any one or more of the following features, configurations and / or additional components.

[0029] In a further embodiment of the above system, the feedback network may include a feedback resistor in series with a feedback capacitor, the feedback capacitor also connected to the output terminal of the transistor, and the feedback resistor also connected to the input terminal of the transistor.

[0030] In a further embodiment of any of the aforementioned systems, the input bias circuitry can provide an input bias signal to the series connection of the feedback resistor and the feedback capacitor.

[0031] In a further embodiment of any of the aforementioned systems, a fixed LC series network can electrically couple an output terminal of the transistor of the first transconductance cell and an input terminal of the transistor of the second transconductance cell.

[0032] In a further embodiment of any of the aforementioned systems, each transistor of the first transconductance cell and the second transconductance cell may be a field effect transistor having a source terminal, a gate terminal functioning as an input terminal, and a drain terminal functioning as an output terminal.

[0033] In a further embodiment of any of the aforementioned systems, the tunable LC series network can electrically couple a drain terminal of the field effect transistor of the first transconductance cell and a source terminal of the field effect transistor of the second transconductance cell.

[0034] In a further embodiment of any of the aforementioned systems, the tunable LC series network can include a plurality of selectable tuning capacitor pairs and a selection transistor electrically coupled between each of the plurality of selectable tuning capacitor pairs, thereby providing selectable tuning to the tunable LC series network.

[0035] In a further embodiment of any of the aforementioned systems, the multiple selectable tuning capacitor pairs can be coupled in a parallel manner.

[0036] Further embodiments of any of the above systems may further include first and second output bias circuitry for the transistors of the first and second transconductance cells, respectively, the first output bias circuitry injecting a bias current into the drain of the transistor of the first transconductance cell via a fixed LC series network connected thereto.

[0037] In a further embodiment of any of the aforementioned systems, the second output bias circuitry can inject a bias current into the drain of the transistor of the second transconductance cell.

[0038] Some embodiments relate to a cascaded low noise wideband phase shifter including a plurality of cascaded low noise wideband active phase shift stages. Each low noise wideband active phase shift stage includes a first and a second transconductance cell. Each of the first and second transconductance cells includes a transistor, a feedback network, and input and output biasing networks. The transistor has an input terminal and an output terminal. The feedback network electrically couples the input terminal and the output terminal of the transistor. The input biasing network and the output biasing network input and output bias the transistor, respectively. A fixed LC series network is connected between the first transconductance cell and the second transconductance cell. A tunable LC series network is connected between the first transconductance cell and the second transconductance cell. The fixed LC series network and the tunable LC series network form an all-pass lattice network together with the first and second transconductance cells.

[0039] The method of the preceding paragraph may optionally and / or alternatively include any one or more of the following features, configurations and / or additional components.

[0040] In a further embodiment of the above method, a first stage of a plurality of cascaded low noise wideband active phase shift stages may provide coarse adjustment of the phase shift between zero and 180 degrees.

[0041] In a further embodiment of any of the aforementioned methods, a second stage of the cascaded plurality of low noise wideband active phase shift stages may provide fine adjustment of the phase shift between zero and 11.25 degrees.

[0042] In a further embodiment of any of the foregoing methods, a third stage of the cascaded plurality of low noise wideband active phase shift stages may provide a binary adjustment of zero or 180 degrees of phase shift.

[0043] In a further embodiment of any of the aforementioned methods, an input bias network can be coupled to the series connection of the feedback resistor and the feedback capacitor.

[0044] In a further embodiment of any of the aforementioned methods, a fixed LC series network may electrically couple an output terminal of a transistor of the first transconductance cell and an input terminal of a transistor of the second transconductance cell.

[0045] In a further embodiment of any of the aforementioned methods, the transistors of each of the first transconductance cell and the second transconductance cell may be field effect transistors having a source terminal, a gate terminal functioning as an input terminal, and a drain terminal functioning as an output terminal.

[0046] In a further embodiment of any of the aforementioned methods, the tunable LC series network can electrically couple a drain terminal of the field effect transistor of the first transconductance cell and a source terminal of the field effect transistor of the second transconductance cell.

[0047] In a further embodiment of any of the aforementioned methods, the tunable LC series network may include a plurality of selectable tuning capacitor pairs and a selection transistor electrically coupled between each of the plurality of selectable tuning capacitor pairs, thereby providing selectable tuning to the tunable LC series network.

[0048] In a further embodiment of any of the foregoing methods, the multiple selectable tuning capacitor pairs may be coupled in a parallel manner.

[0049] Although the present invention has been described with reference to the exemplary embodiment(s), those skilled in the art will recognize that various modifications can be made and equivalents can be substituted for elements of the embodiments without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment(s) disclosed, but will include all embodiments falling within the scope of the appended claims.

Claims

1. a first transconductance cell and a second transconductance cell, each of which comprises: a transistor having an input terminal and an output terminal; a feedback network electrically coupling the input terminal and the output terminal of the transistor; and input bias circuitry and output bias circuitry providing input and output bias, respectively, for the transistors; the first transconductance cell and the second transconductance cell, a fixed LC series network connected between the first transconductance cell and the second transconductance cell; a tunable LC series network connected between the first transconductance cell and the second transconductance cell; Including, the fixed LC series network and the tunable LC series network together with the first transconductance cell and the second transconductance cell form an all-pass lattice network. Low noise wideband active phase shifter.

2. 2. The low noise wideband active phase shifter of claim 1, wherein the feedback network includes a feedback resistor in series with a feedback capacitor, the feedback capacitor also connected to the output terminal of the transistor, and the feedback resistor also connected to the input terminal of the transistor.

3. 2. The low noise wideband active phase shifter of claim 1, wherein the input bias network provides an input bias signal to a series connection point of the feedback resistor and the feedback capacitor.

4. 2. The low noise wideband active phase shifter of claim 1, wherein the fixed LC series network electrically couples the output terminal of the transistor of the first transconductance cell and the input terminal of the transistor of the second transconductance cell.

5. 2. The low noise wideband active phase shifter of claim 1, wherein the transistors of each of the first transconductance cell and the second transconductance cell are field effect transistors having a source terminal, a gate terminal functioning as the input terminal, and a drain terminal functioning as the output terminal.

6. 6. The low noise wideband active phase shifter of claim 5, wherein the tunable LC series network electrically couples the drain terminal of the field effect transistor of the first transconductance cell and the source terminal of the field effect transistor of the second transconductance cell.

7. 2. The low noise wideband active phase shifter of claim 1, wherein the tunable LC series network includes a plurality of selectable tuning capacitor pairs and a selection transistor electrically coupled between each of the plurality of selectable tuning capacitor pairs, thereby providing selectable tuning to the tunable LC series network.

8. 8. The low noise wideband active phase shifter of claim 7, wherein the plurality of selectable tuning capacitor pairs are coupled in a parallel manner.

9. further comprising first and second output bias circuitry for the transistors of the first and second transconductance cells, respectively; 2. The low noise wideband active phase shifter of claim 1, wherein the first output bias network injects a bias current into the drain of the transistor of the first transconductance cell through the fixed LC series network connected thereto.

10. 2. The low noise wideband active phase shifter of claim 1, wherein the second output bias network injects a bias current into the drain of the transistor of the second transconductance cell.

11. A cascaded low noise wideband phase shifter comprising a plurality of cascaded low noise wideband active phase shift stages, Each of the cascaded low noise wideband active phase shift stages comprises: a first transconductance cell and a second transconductance cell, each of which comprises: a transistor having an input terminal and an output terminal; a feedback network electrically coupling the input terminal and the output terminal of the transistor; and input bias circuitry and output bias circuitry providing input and output bias, respectively, for the transistors; the first transconductance cell and the second transconductance cell, a fixed LC series network connected between the first transconductance cell and the second transconductance cell; a tunable LC series network connected between the first transconductance cell and the second transconductance cell; Including, the fixed LC series network and the tunable LC series network together with the first transconductance cell and the second transconductance cell form an all-pass lattice network. Cascaded low noise wideband phase shifters.

12. 12. The cascaded low noise wide band phase shifter of claim 11, wherein a first stage of the cascaded plurality of low noise wide band active phase shift stages provides a coarse adjustment of the phase shift between zero and 180 degrees.

13. 12. The cascaded low noise wide band phase shifter of claim 11, wherein a second stage of the cascaded plurality of low noise wide band active phase shift stages provides fine adjustment of the phase shift between zero and 11.25 degrees.

14. 12. The cascaded low noise wide band phase shifter of claim 11, wherein a third stage of the cascaded plurality of low noise wide band active phase shift stages provides zero or 180 degrees binary adjustment of phase shift.

15. The cascaded low noise wideband phase shifter of claim 11 , wherein the input bias network is coupled to the series junction of the feedback resistor and the feedback capacitor.

16. 12. The cascaded low noise wideband phase shifter of claim 11, wherein the fixed LC series network electrically couples the output terminal of the transistor of the first transconductance cell and the input terminal of the transistor of the second transconductance cell.

17. 12. The cascaded low noise wideband phase shifter of claim 11, wherein the transistors of each of the first transconductance cell and the second transconductance cell are field effect transistors having a source terminal, a gate terminal functioning as the input terminal, and a drain terminal functioning as the output terminal.

18. 12. The cascaded low noise wideband phase shifter of claim 11, wherein the tunable LC series network electrically couples the drain terminal of the field effect transistor of the first transconductance cell and the source terminal of the field effect transistor of the second transconductance cell.

19. 12. The cascaded low noise wideband phase shifter of claim 11, wherein the tunable LC series network includes a plurality of selectable tuning capacitor pairs and a selection transistor electrically coupled between each of the plurality of selectable tuning capacitor pairs, thereby providing selectable tuning to the tunable LC series network.

20. 20. The cascaded low noise wideband phase shifter of claim 19, wherein the plurality of selectable tuning capacitor pairs are coupled in a parallel manner.

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