Variable phase shifter and a system using variable phase shifter

A smart antenna front end system comprising:

• a receiver for receiving an RF receiving signal from an antenna, the receiver including first and second variable phase shifter;
• a transmitter for transmitting an RF transmitting signal from the antenna, the transmitter including third and forth variable phase shifter;
• each of the first, second, third and forth variable phase shifter including:
• an input node for receiving an input signal;
• a first path and a second path for performing analog signal processing;
• an output node for combining the outputs of the first path and the second path to provide an output signal;
• the first path including a first fixed phase shift element for shifting the phase of the input signal by a first shift value, and a first active device for amplifying the output of the first phase shift element, the first active device being inductively coupled to a ground via a first element of the first fixed phase shift element;
• the second path including a second fixed phase shift element for shifting the phase of the input signal by a second shift value, and a second active device for amplifying the output of the second phase shift element, the second active device being inductively coupled to a ground via a second element of the second fixed phase shift element;
• and
• a bias controller for generating first and second bias signals in response to a phase control signal for controlling amplification of the first and second active devices.

A smart antenna front end system comprising:

• a local oscillator path including an local oscillator, and first and second variable phase shifter for shifting the phase of an input signal output from the local oscillator;
• a receiver for receiving an RF receiving signal from an antenna, the receiver including a first mixer for mixing the RF receiving signal and the output of the first variable phase shifter, and a second mixer for mixing the RF receiving signal and the output of the second variable phase shifter;
• a transmitter for transmitting an RF transmitting signal from the antenna, the transmitter including a third mixer for mixing an IF signal and the output of the first variable phase shifter, and a fourth mixer for mixing the IF signal and the output of the second variable phase shifter;
• each of the first and second variable phase shifter including:
• an input node for receiving an input signal;
• a first path and a second path for performing analog signal processing;
• an output node for combining the outputs of the first path and the second path to provide an output signal;
• the first path including a first fixed phase shift element for shifting the phase of the input signal by a first shift value, and a first active device for amplifying the output of the first phase shift element, the first active device being inductively coupled to a ground via a first element of the first fixed phase shift element;
• the second path including a second fixed phase shift element for shifting the phase of the input signal by a second shift value, and a second active device for amplifying the output of the second phase shift element, the second active device being inductively coupled to a ground via a second element of the second fixed phase shift element;
• and
• a bias controller for generating first and second bias signals in response to a phase control signal for controlling amplification of the first and second active devices.

A differential phase shifter comprising:

• first and second variable phase shifters for receiving input signals, each of the input signals being similar in amplitude and 1800 out of phase;
• each of the first and second variable phase shifters including:
• an input node for receiving the corresponding input signal;
• a first path and a second path for performing analog signal processing,
• an output node for combining the outputs of the first path and the second path to provide an output signal;
• the first path including a first fixed phase shift element for shifting the phase of the input signal by a first shift value, and a first active device for amplifying the output of the first phase shift element, the first active device being inductively coupled to a ground via a first element of the first fixed phase shift element;
• the second path including a second fixed phase shift element for shifting the phase of the input signal by a second shift value, and a second active device for amplifying the output of the second phase shift element, the second active device being inductively coupled to a ground via a second element of the second fixed phase shift element;
• and
• a bias controller for generating first and second bias signals in response to a phase control signal for controlling amplification of the first and second active devices.