Zarlink Semiconductor Limited

Mitel Semiconductor Limited

Plessey Semiconductors Limited

Arshad Madni

Nicholas Paul Cowley

Lance Rhys Trodd

Ian G Watson

Franco Lauria

Mark Stephen John Mudd

Mark Mudd

Keith Strickland

Chris Powell

An analogue single conversion tuner comprises a plurality of channels () for covering the whole of a desired reception bandwidth. Each tuner comprises an image reject mixer () connected to the tuner input () by a single tracking filter (), for example of the single-tuned type.

Tuner

An LNA for use as an input stage of a radio frequency tuner comprises an inverting amplifier stage and a transconductance stage. The amplifier stage has an input connected via an input resistance to an input of the amplifier and via a feedback resistance to an output of the amplifier stage. The transconductance stage passes a current through the input resistance which is substantially proportional to the output voltage of the amplifier stage.

Amplifier and radio frequency tuner

A radio frequency amplifier of improved intermodulation performance is provided by connecting first and second transconductance amplifiers in antiphase so that third order intermodulation products cancel each other but the reduction in gain is relatively small. The transconductance stages comprise long tail pairs of transistors provided with tail current sources formed by transistors whose bases are connected to a bias voltage source. The first transistor has an emitter connected via a resistor to ground. The second transistor has an emitter connected via another resistor to the emitter of the first transistor.

Radio frequency amplifier with improved intermodulation performance

An amplifier which is suitable for use as a radio frequency low noise amplifier comprises first, second and third transconductance stages. The amplifier input is connected to the inputs of the first and third stages, whose outputs are connected together in anti-phase so as to provide feedforward error correction. The second stage has inputs connected to the outputs of the first stage and outputs connected across a resistor to current feedback inputs of the first stage so as to provide negative feedback. The first and third stages provide feedforward distortion cancelling so as to improve the linearity of the amplifier. The negative feedback provided by the second stage further improves the linearity without substantially increasing the noise figure of the amplifier.

Amplifier and tuner

A radio frequency amplifier including a long tail pair of transistors provided with a tail current source. The bases of the transistors are driven by emitter follower transistor provided with collector load resistors. Feedback capacitors ensure stability and feedback resistors bias the amplifier without degrading noise performance. The amplifier may be driven unbalanced while retaining good second harmonic distortion performance.

Radio frequency amplifier and television tuner

A system and method are provided for designing and manufacturing a semiconductor device, such as part of an integrated circuit. A template comprising a basic circuit diagram of a discrete circuit block and corresponding design equations are selected from a library. Desired performance parameters are selected and the value of one or more components of the circuit block are determined to allow the block to achieve the desired performance parameters.

System for and method of designing and manufacturing a semiconductor device

A radio frequency amplifier includes first and second transconductance stages , the product of whose transconductances is negative. The input and output of the first stage form the input and output of the amplifier. The output of the first stage is provided with a load whereas the output of the second stage is provided with a load and is fed back to the input of the first stage.

Radio frequency amplifier and tuner

An AC voltage amplifier arrangement comprising an input stage having an input, an amplifier connected in series shunt feedback mode, and an output, further comprises a variable gain amplification stage having an input coupled to the output of said input stage , and an output. The amplifiers of the input and variable gain amplification stages are arranged to operate in current mode.

Amplifiers

A radio frequency amplifier comprises an input amplifier provided with a shunt feedback path for determining the input impedance. A first transconductance amplifier forms part of a series feedback arrangement with a resistor around the amplifier so as to boost the effective value of the resistor. An identical transconductance amplifier is connected to the output of the input amplifier and its output forms the output of the radio frequency amplifier.

Radio frequency amplifier

A variable transconductance amplifier comprises transistors and whose emitters are connected via resistors and to a constant current source to form a differential or long tail pair. A feedback amplifier whose transconductance is controllable has inputs connected to the collectors of the transistors and outputs connected to the emitters thereof. The feedback amplifier thus supplies a differential current to the emitters of the transistors which corresponds to the product of the differential output signal of the transistors and the variable transconductance of the feedback amplifier.

Variable transconductance amplifier

A voltage to current converter comprises a first long tail pair comprising transistors whose emitters are connected via equal value resistors to a constant current source. The first long tail pair forms a main transconductance stage. A subsidiary or corrector transconductance stage is connected in anti-phase with the main stage. The corrector stage is based on another long tail pair comprising transistors whose emitters are connected via resistors to another constant current source. The linear part of the transconductance of the corrector stage is substantially less than that of the main stage but the non-linear part is substantially equal to that of the main stage. Thus, non-linear distortion can be substantially reduced.

Voltage to current converter

In an amplifier circuit arrangement in which series resistive feedback is utilized in the main amplifier to minimize distortion, and a feedback amplifier is provided in a path from the output of the arrangement to the series feedback path effectively to boost the value of the feedback resistor, a further amplifier is arranged to provide positive feedback to the resistive load circuit of the main amplifier effectively to boost the value of the resistive load.

Dual-feedback amplifier circuit arrangements

An amplifier arrangement comprising a plurality of similar amplifier stages to which input signal voltages are applied in common, the output signal voltages being summed to retain bandwidth at the expense of gain compared with cascaded stages. The individual stages of the arrangement may be cascoded amplifier stages.

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Swindon, United Kingdom

Arshad Madni