Abstract: An analogue single conversion tuner comprises a plurality of channels (1, 2, 3) for covering the whole of a desired reception bandwidth. Each tuner comprises an image reject mixer (18) connected to the tuner input (4) by a single tracking filter (16), for example of the single-tuned type.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A radio frequency amplifier includes first and second transconductance stages 20, 21, 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 22 whereas the output of the second stage 21 is provided with a load 23 and is fed back to the input of the first stage.

Abstract: 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.

Abstract: An input interface is provided for interfacing between a radio frequency input, for example from a cable distribution network, and a plurality of radio frequency tuners. The interface comprises a broadband active multipath non-reactive power splitter having an input for receiving a broadband radio frequency signal and a plurality of differential outputs. The splitter further has an active power splitting circuit which supplies the broadband radio frequency signal to each of the outputs via a channel comprising an automatic gain control circuit having a single-ended output connected to the input of a differential output buffer.

Abstract: An AC voltage amplifier arrangement comprising an input stage 1 having an input, an amplifier 3 connected in series shunt feedback mode, and an output, further comprises a variable gain amplification stage 2 having an input coupled to the output of said input stage 1, and an output. The amplifiers 3, 5 of the input and variable gain amplification stages 1, 2 are arranged to operate in current mode.

Abstract: A technique is provided for making a semiconductor device having a first circuit block. This technique comprises analysing the first circuit block to determine its transfer function. The transfer function is then rearranged to resemble a known type of transfer function of a simpler circuit block whose performance is a known function of one of more parameters of the second transfer function. The value of the or each parameter which achieves a desired performance is derived from the known function and is used to calculate component values of the circuit block to be made so as to form a design. The design is then acted on so as to manufacture the device.

Abstract: 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.

Abstract: A method is provided for manufacturing a semiconductor device. A design file is selected from a library and contains a design of a circuit block. A process file containing information about a manufacturing process including performance information about the performance of one or more of the components produced by the manufacturing process is selected from another library. The desired performance specification from the circuit block is defined. Operation of the circuit block is then simulated using the performance information from the process file and the simulation result is compared with the desired performance specification. If the performance specification is achieved, the design is used to manufacture the semiconductor device.

Abstract: 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.

Abstract: An analogue single conversion tuner comprises a plurality of channels (1, 2, 3) for covering the whole of a desired reception bandwidth. Each tuner comprises an image reject mixer (18) connected to the tuner input (4) by a single tracking filter (16), for example of the single-tuned type.

Abstract: 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.

Abstract: A radio frequency amplifier comprises first and second transconductance stages 20, 21, 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 22 whereas the output of the second stage 21 is provided with a load 23 and is fed back to the input of the first stage.

Abstract: 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.