Mobile telephone apparatus with tunable filter tuned to the transmit band
AssigneeNEC Corporation
InventorNigel J Tolson
Life of this patent
Estimating the term…
Abstract
A mobile phone apparatus which is capable of meeting the stringent specifications on transmitter noise in the receive band. The mobile phone apparatus has a modulator for producing a signal to be transmitted in a transmit band, a power amplifier for supplying the signal to be transmitted to an aerial, a tunable filter disposed between the modulator and the power amplifier and having a passband and an attenuation band, and a control circuit for tuning the filter such that the passband is at the transmit band and the attenuation band is at a receive band of the apparatus.
Claims3
A mobile phone apparatus comprising:
- a modulator for producing a signal to be transmitted in a transmit band;
- a power amplifier for supplying the signal to be transmitted to an aerial;
- a tunable filter disposed between the modulator and the power amplifier and having a passband and an attenuation band;
- and
- a control circuit for tuning the filter such that the passband is at the transmit band and the attenuation band is at a receive band of the apparatus;
- wherein the filter is voltage tunable,
- wherein the control circuit comprises a power detector connected to the output of the filter and a control loop for varying the tuning voltage of the filter until a predetermined power is detected,
- wherein the control loop comprises a signal generator for generating a varying voltage for the filter and a feedback circuit whose input is connected to the power detector and whose output is superimposed on the varying voltage, and
- wherein the feedback circuit comprises a multiplier whose inputs are connected to the power detector and the signal generator and a comparator for comparing the output of the multiplier with a reference level corresponding to the predetermined power.
A mobile phone apparatus comprising:
- a modulator for producing a signal to be transmitted in a transmit band;
- a power amplifier for supplying the signal to be transmitted to an aerial;
- a tunable filter disposed between the modulator and the power amplifier and having a passband and an attenuation band;
- and
- a control circuit for tuning the filter such that the passband is at the transmit band and the attenuation band is at a receive band of the apparatus;
- wherein the filter is a bandpass filter,
- wherein the filter is voltage tunable,
- wherein the control circuit comprises a power detector connected to the output of the filter and a control loop for varying the tuning voltage of the filter until a predetermined power is detected,
- wherein the control loop comprises a signal generator for generating a varying voltage for the filter and a feedback circuit whose input is connected to the power detector and whose output is superimposed on the varying voltage, and
- wherein the feedback circuit comprises a multiplier whose inputs are connected to the power detector and the signal generator and a comparator for comparing the output of the multiplier with a reference level corresponding to the predetermined power.
Dependencies are inferred from the claim text.