Amplification circuit

摘要

An amplification circuit, which may be in a receive path of a communication device, includes an amplifier including at least a first amplification device and a switchable attenuation circuit. The switchable attenuation circuit includes one or more switches and a plurality of attenuation devices and is operable to provide different levels of attenuation to an input signal prior to input to the amplifier depending on the status of the one or more switches. The attenuation devices may be capacitors, wherein the capacitors may be arranged to form a capacitive divider with a level of attenuation dependent on the status of the switches. The switchable attenuation circuit may be a switched capacitive attenuation ladder of n stages, n being any integer, each ladder stage including a capacitive divider. The amplification circuit may also include a switch, which when closed provides an unattenuated path for the input signal to the amplifier input.

主权项

1. An amplification circuit comprising;
an amplifier having an input and an output; and a switchable attenuation circuit configured to provide different levels of attenuation to an input signal prior to input to the amplifier, the switchable attenuation circuit comprising a switched capacitive attenuation ladder of n stages, n being any integer, each ladder stage including a capacitive divider formed by two capacitors, a first of the two capacitors connected in series with a differing ladder stage and a second of the two capacitors coupled to a reference node, and a switch for selective connection of the output of each capacitive divider to the amplifier input, the circuit being configured such that no more than one switch is closed at any time, the attenuation applied to the input signal being dependent on which of the switch is closed.