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US 5,293,139 AGranted
CMOS-compander
AssigneeNokia Mobile Phones Ltd.
InventorsJouni Polonen, Mika Gronroos, Kim Kaltiokallio
Life of this patent
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Abstract
The invention relates to a compressor and an expander for use in a compander realized in CMOS-technology which is used to improve speech quality in mobile phone systems AMPS (NAMPS), NMT and TACS (JTACS, ETACS, NTACS). The compander is integrated with other functions of the mobile phone. The compressor and expander have SC-amplifiers controlled by a control logic. A double comparator XOR-block is used in the control of the amplifiers.
Claims14
A compressor comprising:
- a first controlled amplifier having signal input and signal output means;
- a second controlled amplifier, the input of which is connected to the output of the first amplifier, the amplifiers being switched capacitor (SC) amplifiers;
- a level detection circuit, for detecting the level of the second amplifier output signal;
- and
- a control circuit controlling the first and the second amplifiers responsive to the level detection circuit,
- characterized in that
- the level detection circuit includes means for comparing the detected level of the second amplifier output signal with an upper (+Uref) and a lower (-Uref) reference voltage, the output of the detection circuit having a first value when the detected signal level lies in a zone between the reference voltages, and having a second value when the input signal lies outside the zone between the reference voltages, and
- the control circuit comprises counting means in which the counting direction is determined according to the value of the detection circuit output, and in which the counting result is used to generate a control word for the amplifiers.
5 more elements
An expander comprising:
- a first controlled amplifier having signal input and signal output means;
- a second controlled amplifier, the input of which is connected to the output of the first amplifier, the amplifiers being switched capacitor (SC) amplifiers;
- a level detection circuit, for detecting the level of the second amplifier output signal;
- and
- a control circuit controlling the first and the second amplifiers responsive to the level detection circuit,
- characterized in that
- the level detection circuit includes means for comparing the detected level of the second amplifier output signal with an upper (+Uref) and a lower (-Uref) reference voltage, the output of the detection circuit having a first value when the detected signal level lies in a zone between the reference voltages, and having a second value when the input signal lies outside the zone between the reference voltages, and
- the control circuit comprises counting means in which the counting direction is determined according to the value of the detection circuit output, and in which the counting result is used to generate a control word for the amplifiers.
5 more elements
A compander having a compressor and an expander, the compressor comprising:
- a first controlled amplifier having signal input and signal output means;
- a second controlled amplifier, the input of which is connected to the output of the first amplifier, the amplifiers being switched capacitor (SC) amplifiers;
- a level detection circuit, for detecting the level of the second amplifier output signal;
- and
- a control circuit controlling the first and the second amplifiers responsive to the level detection circuit,
- characterized in that
- the level diction circuit includes means for comparing the detected level of the second amplifier output signal with an upper (+Uref) and a lower (-Uref) reference voltage, the output of the detection circuit having a first value when the detected signal level lies in a zone between the reference voltages, and having a second value when the input signal lies outside the zone between the reference voltages, and
- the control circuit comprises counting means in which the counting direction is determined according to the value of the detection circuit output, and in which the counting result is used to generate a control word for the amplifiers.
5 more elements
A compander having a compressor and an expander, the expander comprising:
- a first controlled amplifier having signal input and signal output means;
- a second controlled amplifier, the input of which is connected to the output of the first amplifier, the amplifiers being switched capacitor (SC) amplifiers;
- a level detection circuit, for detecting the level of the second amplifier output signal;
- and a control circuit controlling the first and the second amplifiers responsive to the level detection circuit,
- characterized in that
- the level detection circuit includes means for comparing the detected level of the second amplifier output signal with an upper (+Uref) and a lower (-Uref) reference voltage, the output of the detection circuit having a first value when the detected signal level lies in a zone between the reference voltages, and having a second value when the input signal lies outside the zone between the reference voltages, and
- the control circuit comprises counting means in which the counting direction is determined according to the value of the detection circuit output, and in which the counting result is used to generate a control word for the amplifiers.
4 more elements
Dependencies are inferred from the claim text.