Amplifying circuit with adjustable amplification and transmitter system comprising such an amplifying circuit
First Claim
1. An amplifier circuit with adjustable gain, comprising:
- an input terminal pair configured to receive a differential input signal;
an output configured to output an amplified version of the differential input signal;
a control input configured to supply a gain factor to the amplifier circuit;
a cascode stage connected to the output and comprising two cascode transistors coupled together at a control terminal thereof;
a plurality of differential amplifiers connected together in parallel, each comprising a respective differential input connected to the input terminal pair, a respective differential output connected to the cascode stage, and a respective activation input, and wherein each differential amplifier further comprises two differential amplifier transistors coupled to a current mirror transistor, and wherein the current mirror transistor is coupled to the activation input and, together with the differential amplifier transistors, is configured to supply a reference current based on a signal at the activation input; and
an actuation unit comprising an input connected to the control input of the amplifier circuit, and a plurality of outputs, a respective one of which is connected to the activation input of a respective differential amplifier, and configured to selectively activate one or more differential amplifiers based on the gain factor supplied at the control input.
1 Assignment
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Accused Products
Abstract
The invention is directed to an amplifier circuit with adjustable gain which includes a plurality of parallel-connected differential amplifiers connected to a common cascode stage. An actuation unit is used to activate the differential amplifiers independently of one another on the basis of an applied control signal. The principle described makes it possible to dispense with inductances in the differential amplifier and hence to reduce unwanted crosstalk, while having a high linearity. Secondly, the amplifier'"'"'s drawn current matches the respective output power which can be tapped off. Overall, the principle described is particularly suitable for use in UMTS mobile radios.
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Citations
19 Claims
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1. An amplifier circuit with adjustable gain, comprising:
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an input terminal pair configured to receive a differential input signal;
an output configured to output an amplified version of the differential input signal;
a control input configured to supply a gain factor to the amplifier circuit;
a cascode stage connected to the output and comprising two cascode transistors coupled together at a control terminal thereof;
a plurality of differential amplifiers connected together in parallel, each comprising a respective differential input connected to the input terminal pair, a respective differential output connected to the cascode stage, and a respective activation input, and wherein each differential amplifier further comprises two differential amplifier transistors coupled to a current mirror transistor, and wherein the current mirror transistor is coupled to the activation input and, together with the differential amplifier transistors, is configured to supply a reference current based on a signal at the activation input; and
an actuation unit comprising an input connected to the control input of the amplifier circuit, and a plurality of outputs, a respective one of which is connected to the activation input of a respective differential amplifier, and configured to selectively activate one or more differential amplifiers based on the gain factor supplied at the control input. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An amplifier circuit, comprising:
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a plurality of differential amplifier circuits coupled together in parallel between a differential signal input and a differential signal output, wherein each of the differential amplifier circuits comprises an activation input, and wherein each of the differential amplifier circuits is configured to be individually activated or deactivated based on a state of an activation signal thereat;
a cascode stage output circuit having a differential input coupled to the differential signal output, and a differential output forming an output of the amplifier circuit; and
an actuation unit having a control input configured to receive a control input signal indicative of a gain of the amplifier circuit, and a plurality of activation outputs respectively coupled to the activation inputs of the differential amplifier circuits, wherein the actuation unit is configured to activate a selected one or more differential amplifier circuits via a state of the activation outputs based on the control input signal and a predetermined allocation rule. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A transmission arrangement, comprising:
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a radio-frequency mixer configured to convert a baseband signal, which has been split into in-phase and quadrature components, to a radio frequency signal; and
an amplifier circuit, having an input terminal pair connected to an output of the radio-frequency mixer, and configured to amplify a radio-frequency signal at the output of the radio-frequency mixer using an adjustable gain factor, the amplifier circuit comprising;
a plurality of differential amplifier circuits coupled together in parallel between the input terminal pair and a differential signal output, wherein each of the differential amplifier circuits comprises an activation input, and wherein each of the differential amplifier circuits is configured to be individually activated or deactivated based on a state of an activation signal thereat;
a cascode stage output circuit having a differential input coupled to the differential signal output, and a differential output forming an output of the amplifier circuit; and
an actuation unit having a control input configured to receive a control input signal indicative of a gain of the amplifier circuit, and a plurality of activation outputs respectively coupled to the activation inputs of the differential amplifier circuits, wherein the actuation unit is configured to activate a selected one or more differential amplifier circuits via a state of the activation outputs based on the control input signal and a predetermined allocation rule. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification