Abstract: The invention describes improvements to a balanced active demodulator subsystem implemented in Radio Frequency integrated circuit technology that simplify the configuration and set-up of a balanced demodulator section and reduce the labor and time required during manufacture to adjust the demodulation characteristics for optimum performance.

Abstract: A method of measuring changes in signal level output of an integrated circuit sensor by providing a direct current (DC) or low frequency (AC) bias to the sensor and placing a floating gate semiconductor device on-chip and coupling the floating gate of the semiconductor device with the sensor. As a result, changes in signal level output of the sensor modulate charge at the gate. The semiconductor device in turn converts the modulated charge at the gate into output signals proportional to the changes in the signal level output. The measurement method provides a resolution in the sub-atto range.

Abstract: A signal convertor for modulating or demodulating an input signal x(t), comprising: a synthesizer for generating wideband mixing signals &phgr;1 and &phgr;2, which vary irregularly over time, where &phgr;1*&phgr;2 has significant power at the frequency of a local oscillator signal being emulated; a first mixer coupled to said synthesizer for mixing said input signal x(t) with said mixing signal &phgr;1 to generate an output signal x(t) &phgr;1; and a second mixer coupled to said synthesizer and to the output of said first mixer for mixing said signal x(t) &phgr;1 with said mixing signal &phgr;2 to generate an output signal x(t) &phgr;1 &phgr;2.

Abstract: An integrated RF filter for use at microwave frequencies comprising: an integrated circuit inductor with connected integrated circuit capacitors, arranged as a tank circuit, and an integrated circuit shunt resistor; the inductor, capacitors and resistor being interconnected in a bridge-T filter arrangement.

Abstract: A method of performing a frequency conversion of a radio frequency (RF) information signal by mixing the information signal with a modulated signal from local oscillator. The local oscillator signal is modulated with a periodic, coded or pseudo-random modulating signal. A system for generating an intermediate frequency (IF) output signal from the information signal is also provided.

Abstract: An integrated radio frequency (RF) coupling scheme is provided for realizing low voltage RF integrated circuits. According to the invention, on-chip capacitively coupled resonant elements are used to DC isolate circuit block elements which are required to be connected in series and share a common DC current. The coupling scheme according to the present invention may be applied to several commonly used RF integrated circuit topologies such as low noise amplifiers and mixers.

Abstract: An RF direct down-conversion topology that is insensitive to leakage and device mismatching is presented. According to the system the RF signal is split into two arms with each arm having a mixer. Each mixer has two inputs namely a phase modulated local oscillator signal and the RF information signal. The phase modulated local oscillator signal between each arm differs by a 90 degrees phase shift. The output of the mixers is subtracted and the output of the subtractor is mixed with the phase modulation signal. The output of the third mixer represents the base band. A low pass filter then removes the unwanted signals.

Abstract: A low voltage cascode frequency conversion mixer circuit is provided. In place of a conventional current source, an LC tank circuit is used. This makes the circuit function as a mixer only over a narrow band of frequencies centred at the resonance frequency of the LC tank circuit. The circuit mixes an input signal with a local oscillator signal. Advantageously, a lower supply voltage may be used because a smaller DC drop exists across the tank circuit than does across conventional current sources. The circuit may also be used as an amplifier by connecting a DC bias voltage in place of the local oscillator.

Abstract: A capacitance measuring device comprises a MOS transistor having a source, drain, and gate; a first capacitor C.sub.1 connected between said gate and said drain so that charge is coupled from said drain onto said gate; and a second capacitor C.sub.2 for connection to a source of gate voltage V.sub.G and connected to said gate. One of the first and second capacitors has a known capacitance and the other has an unknown capacitance. A DC voltage is supplied between the source and drain to cause a saturation current to flow therebetween. The ratio .delta.V.sub.G /.delta.V.sub.d for the saturation current, where V.sub.G is the applied gate voltage, and V.sub.d is the drain voltage is determined and the unknown capacitance is derived from the relationship C.sub.1 /C.sub.2 =-.delta.V.sub.G /.delta.V.sub.d.

Abstract: A semiconductor test chip has an array of active semiconductor devices to be individually tested, a number of test lines for connection to external test circuitry, an enabling circuit associated with each device for selectively connecting it to the test lines, an input for receiving an instruction identifying a device that it is desired to test, and a decoder incorporated into the chip for receiving the instruction from the input. The decoder is connected by enabling lines to the individual test devices so that on receipt of an instruction the decoder enables the identified test device such that it becomes connected to the test lines. This circuit is more efficient and less cumbersome than the prior art.