Abstract: A level shifter having: an input configured to receive an input signal, an output configured to provide an output signal, a voltage rail configured to provide a rail voltage, at least two diodes including a first and second diode connected in series between the voltage rail and the input, at least three switches, and a capacitor. The at least three switches include a first switch coupled between the voltage rail and the output of the first diode, a second switch coupled between the voltage rail and the output of the second diode, and a third switch coupled between the voltage rail and the input. The capacitor is coupled between the output of the second diode and ground.

Abstract: A start-up circuit for a bandgap reference voltage generator circuit, including a first native transistor with a drain connected to a supply voltage of the bandgap reference voltage generator circuit and a source connected to a gate of the first native transistor; a low voltage transistor with a source connected to ground, a drain connected to the source of the first native transistor, and a gate connected to a resistor; a second native transistor with a source connected to the resistor, a gate connected to the source of the first native transistor; a high voltage transistor with a drain connected to a drain of the second native transistor and a source connected to the supply voltage; and a transistor with a gate connected to the gate of the first high voltage transistor and a drain which provides a start-up current for the bandgap reference voltage generator circuit.

Abstract: A single-chip CMOS direct conversion transceiver includes an RF circuit, a transmitter having a synthesizer, a receiver having a baseband filter, and a demodulator. The synthesizer is coupled to the RF circuit. The baseband filter is coupled to the RF circuit and the synthesizer. The demodulator is coupled to the baseband filter. The RF circuit, the synthesizer, the baseband filter, and the demodulator are arranged and configured in CMOS devices and provide a complete interface between an antenna and a voiceband codec.

Abstract: A VCO system for equalizing a positive frequency deviation and a negative frequency deviation by using two varactors is described. The VCO system includes an active circuit and an oscillating circuit. The active circuit includes a first input, a second input coupled to ground and an output. The oscillating circuit is coupled to the output of the active circuit, including: a first varactor controlled by a first variable voltage; a second varactor controlled by a second variable voltage, connected in parallel to the first varactor; and an inductor connected in parallel to the first varactor and to the second varactor. An output signal of the oscillating circuit is fed back to the first input of the active circuit. The output signal of the oscillating circuit has a variable frequency in response to first and second variable voltages of the first and second varactors, respectively.

Abstract: A conversion circuit in a transceiver system is capable of converting a single-ended input voltage signal to balanced differential output signals. An input voltage signal can be referenced to the ground (zero voltage) GND and can travel both above and below the zero voltage. A plurality of feedback circuits, having a plurality of transistors and a plurality of resistances, disposed and coupled in a mirror image, to boost an input impedance to an output impedance of a gain of one of the transistors, to isolate an output load from an input of the conversion circuit, and to provide a voltage gain from the input to an output determined by the plurality of resistances.