A RF downconverter-tuner system is provided. A RF downconverter-tuner system to convert one or more input signals into a lower range of frequency bands, comprising one or more RF input ports for receiving the one or more input signals, one or more RF output ports for transmitting the output signal and a plurality of dual-mode switches coupled to two or more of the one or more RF input ports, the one or more RF output ports and one or more receive chain comprising one or more mixers for converting the one or more input signals into the lower range of frequency bands, a plurality of filters, a bypass mode, a back-end receiver coupled to the one or more RF output ports, an oscillator implemented with a frequency synthesis circuit, a plurality of amplifier stages, one or more signal detection circuits and a plurality of controller ports.

A transposed delay line oscillator including a mode selection filter and a transposed delay line is provided. An output of the transposed delay line is coupled to an input of the mode selection filter to establish an oscillator loop. Based on the transposed delay line output, the mode selection filter generates a mode selection signal including an isolated oscillatory mode, in a Radio Frequency (RF) band. The transposed delay line receives the mode selection signal for transposition to an intermediate frequency of an intermediate frequency (IF) delay line. The IF delay line includes a delay filter and a phase noise suppression loop configured to suppress de-correlated transposition phase noise resulting from a delay of the delay filter. Suppression of phase noise in the IF delay line enables cancellation of transposition phase noise when transposing the IF delay line output to the RF band.

Methods and apparatus for transmitting signals, the transmitter including a memory storing instructions and a controller configured to execute the instructions to cause the transmitter to determine whether a value of transmitter power is less than a threshold, responsive to a determination that the value of transmitter power is less than the threshold: mix a baseband signal with a first oscillator signal to produce a very-low intermediate frequency (VLIF) signal; mix the VLIF signal with a second oscillator signal to produce a radio frequency (RF) signal, and transmit the RF signal.

An electronic circuit according to the embodiment of the present invention includes a first circuit, a second circuit electrically insulated from the first circuit, and a transmitter transmitting a signal between the first and the second circuits. The first circuit receives an input signal, generates a first reference signal, and converts frequencies of the input signal and the first reference signal. The transmitter transmits the frequency-converted input signal and first reference signal to the second circuit. The second circuit converts the frequencies of the transmitted input signal first reference signal to obtain a restored input signal and a restored first reference signal, generates a second reference signal, calculates a gain to be adjusted of the restored input signal based on the restored first reference signal and the second reference signal to adjust the gain of the restored input signal.

An electronic circuit according to the embodiment of the present invention includes a first circuit, a second circuit electrically insulated from the first circuit, and a transmitter transmitting a signal between the first and the second circuits. The first circuit receives an input signal, generates a first reference signal, and converts frequencies of the input signal and the first reference signal. The transmitter transmits the frequency-converted input signal and first reference signal to the second circuit. The second circuit converts the frequencies of the transmitted input signal first reference signal to obtain a restored input signal and a restored first reference signal, generates a second reference signal, calculates a gain to be adjusted of the restored input signal based on the restored first reference signal and the second reference signal to adjust the gain of the restored input signal.

A mixer circuitry comprises a mixer, a local oscillator (LO) leakage detector, a digital LO leakage cancellation controller and a DAC arrangement. The mixer is configured to mix a first LO signal having an LO frequency f.sub.LO with an intermediate frequency (IF) signal and generate an output signal, i.e. a wanted signal. The LO leakage detector measures the LO leakage at the output of the mixer in the presence of the wanted signal. Then in the digital LO leakage cancellation controller, a digital algorithm is run that automatically adjusts the LO leakage in the mixer by steering the digital-to-analog converter arrangement such that the intermediate frequency input signal level to the mixer is adjusted.

A circulator, comprising: a gyrator having a first side (1S) and a second side (2S) connected to a third port; a first transmission line section (TLS) having a 1 S connected to the 1 S of the gyrator and a 2S connected to a first port; a second TLS having a 1S connected to the first port and having a 2S connected to a second port; a third TLS having a 1S connected to the second port and having a 2S connected to the third port; a first cancellation path (CP) that is connected between the first port and the third port and introduces a current that is 90 degrees out of phase with a first voltage at the first port; and a second CP that is connected between the second port and the third port and introduces a current that is orthogonal to the current introduces by the first CP.

A circuit comprising a differential transmission line and eight switches provides non-reciprocal signal flow. In some embodiments, the circuit can be driven by four local oscillator signals. The circuit can be used to form a gyrator. The circuit can be used to form a circulator. The circuit can be used to form three-port circulator than can provide direction signal flow between a transmitter and an antenna and from the antenna to a receiver. The three-port circulator can be used to implement a full duplex transceiver that uses a single antenna for transmitting and receiving.

A mixer circuitry comprises a mixer, a local oscillator (LO) leakage detector, a digital LO leakage cancellation controller and a DAC arrangement. The mixer is configured to mix a first LO signal having an LO frequency f.sub.LO with an intermediate frequency (IF) signal and generate an output signal, i.e. a wanted signal. The LO leakage detector measures the LO leakage at the output of the mixer in the presence of the wanted signal. Then in the digital LO leakage cancellation controller, a digital algorithm is run that automatically adjusts the LO leakage in the mixer by steering the digital-to-analog converter arrangement such that the intermediate frequency input signal level to the mixer is adjusted.

A double-balanced radio-frequency (RF) mixing digital-to-analog converter (DAC) apparatus includes a load network, a first set of resistive DAC driver circuits and a first mixing core. The first mixing core can receive first RF input signals from the first set of resistive DAC driver circuits and can provide a first mixed signal to the load network. The first mixing core includes a first input differential pair coupled to two first cross-coupled differential pairs. The first input differential pair can receive first RF input signals at respective first input nodes. Each of the two first cross-coupled differential pairs can receive first positive and negative local oscillator (LO) signals at corresponding first input nodes. The first mixing core can mix the first RF input signals with the first positive and negative LO signals.