A circuit for implementing an operational transconductance amplifier (OTA) based on telescopic topology, wherein cascode transistors of the operational transconductance amplifier (OTA) are self-biased without using additional biasing circuitry, which not only reduces power consumption but also achieves high gain without extra current, and each cascode stage of the OTA has a pair of transistors so that the swing of the output differential signals of the OTA can be completely symmetrical so as to benefit second-order harmonic rejection, CMRR and PSRR.

Polyphase gm-C filters can use matching gm cell components for improved higher image rejection results. Polyphase gm-C filter cells all can be matched by incorporating a matching gmu value in each of the g.sub.m components. The matching gmu value used to replace different gm values can be determined for incorporation into each gm cell component of a filter by: calculating coupling of gmi, gmij by gmi=Ci0 and gmij=Czij0 for i,j; calculating K.sub.i=gmi/gmu; rounding K.sub.i to an integer number, Ni=round(Ki), KiNi and Nij=round(Kij), KijNij; calculating a scaling factor for circuit capacitors C.sub.i and Czijby i=(NiKi)/Ki and ij=(NijKij)/Kij; and adjusting circuit capacitors C.sub.i and Czij by CiCi*(1+i) and CzijCzij*(1+ij). Once the process is completed for i,j, the result can be implemented to match gm cell components of traditional and newly designed polyphase gm-C filters with the matching gmu value.

A resonator circuit has first to sixth transconductance units and the first to fourth connectors. The first transconductance unit has the first top, bottom, and control terminals. The second transconductance unit has the second top terminal connected to the first bottom terminal and has the second bottom and control terminals. The third transconductance unit has a third top terminal connected to the first top terminal and has the third bottom and control terminals. The fourth transconductance unit has the fourth top, bottom, and control terminals. The fifth transconductance unit has the fifth top terminal connected to the fourth bottom terminal and has the fifth bottom and control terminals. The sixth transconductance unit has the sixth top terminal connected to the fourth top terminal and has the sixth bottom and control terminals.

A first transistor (2a), a second transistor (2b), a third transistor (2c) and a fourth transistor (2d) are provided. A first transistor (2a) amplifies a first I signal V.sub.IP inputted from a first input terminal (1a). A second transistor (2b) amplifies a first Q signal V.sub.QP inputted from a second input terminal (1b). A third transistor (2c) amplifies a second I signal V.sub.IN when the second I signal V.sub.IN is inputted from a third input terminal (1c), the second I signal V.sub.IN forming a differential signal with the first I signal V.sub.IP. A fourth transistor (2d) amplifies a second Q signal V.sub.QN when the second Q signal V.sub.QN is inputted from a fourth input terminal (1d), the second Q signal V.sub.QN forming a differential signal with the first Q signal V.sub.QP.

A resonator circuit has first to sixth transconductance units and the first to fourth connectors. The first transconductance unit has the first top, bottom, and control terminals. The second transconductance unit has the second top terminal connected to the first bottom terminal and has the second bottom and control terminals. The third transconductance unit has a third top terminal connected to the first top terminal and has the third bottom and control terminals. The fourth transconductance unit has the fourth top, bottom, and control terminals. The fifth transconductance unit has the fifth top terminal connected to the fourth bottom terminal and has the fifth bottom and control terminals. The sixth transconductance unit has the sixth top terminal connected to the fourth top terminal and has the sixth bottom and control terminals.

A low-pass filter circuit comprising: a low-pass filter input terminal; a low-pass filter output terminal; a reference terminal; at least three filter resistors connected in series with each other between the low-pass filter input terminal and the low-pass filter output terminal, such that there is a resistor-connecting-node between each adjacent pair of filter resistors; a plurality of filter capacitors, one for each of the resistor-connecting-nodes, wherein each of the filter capacitors is connected between an associated resistor-connecting-node and the reference terminal; and a branch connected in parallel with the at least three filter resistors, wherein the branch comprises a bridging capacitor and a bridging resistor in series with each other.

The present disclosure provides an apparatus that includes a first mixer circuit configured to convert between an RF signal and an IF signal based at least in part on an local oscillator (LO) signal. The first mixer circuit is electrically coupled to a first node that is configured to receive the LO signal and a first bias voltage, a second node that is configured to receive the RF signal or the IF signal, and a third node that is configured to provide the IF signal or the RF signal. The apparatus further includes a second mixer circuit electrically coupled to a fourth node configured to receive the LO signal and a second bias voltage, the second node, and the third node. The second bias voltage has a voltage level that is offset from the first bias voltage.

A high order filter circuit is integrated by a plurality of the low order filter circuits. Before correcting the high order filter circuit, switch units may restore the high order filter circuit to the low order filter circuits for correction, and then combine the corrected low order filter circuits to form the original high order filter circuit.

There is described herein methods and devices for high DC gain closed loop operation amplifiers exploiting cascaded low gain stages and a controller-based compensation circuit for stability.

Self-interference cancellers are provided. The self-interference cancellers can include multiple second-order, N-path G.sub.m-C filters. Each filter can be configured to cancel self-interference on a channel of a desired bandwidth. Each filter can be independently controlled using a variable transmitter resistance, a variable receiver resistance, a variable baseband capacitance, a variable transconductance, and a variable time shift between local oscillators that control switches in the filter. By controlling these variables, magnitude, phase, slope of magnitude, and slope of phase of the cancellers frequency responses can be controlled for self-interference cancellation. A calibration process is also provided for configuring the canceller.