公开(公告)号：BR0206834A

公开(公告)日：2004-12-28

申请号：BR0206834

申请日：2002-01-30

Applicant: QUALCOMM INC

Inventor： BAZARJANI SEYFOLLAH ,  GOLDBLATT JEREMY

IPC: G05F3/26 ,  G05F3/20 ,  H03F3/45

Abstract: A bias circuit is described for use in biasing an operational amplifier to maintain a constant transconductance divided by load capacitance (i.e. a constant gm/CL) despite temperature and process variations and despite body effects. In one example, the bias circuit includes a pair of current source devices and a switched capacitor (SC) equivalent resistor circuit for developing an equivalent resistance between the current source devices. The equivalent resistor circuit includes a sampling capacitor. First and second clock inputs are connected to the capacitor providing non-overlapping clock signals at a predetermined sampling frequency to establish a resistance equivalent. By providing an SC equivalent resistor circuit clocked by non-overlapping fixed clock signals, the gm/CL of the bias circuit is maintained substantially constant. Hence, a fixed bandwidth is maintained within the operational amplifier being biased. When employed in connection with operational amplifiers of an SC circuit, the constant bandwidth enables the SC circuit to operate at a constant switching speed despite temp and process variations. Furthermore, by positioning the resistance equivalent circuit between the current source devices of the bias circuit, voltage differentials between the sources are eliminated thereby removing any threshold voltage mismatch and thus compensating for body effect variations. Other bias circuit examples are also described including a stray insensitive bias circuit and a bias circuit employing three mutually non-overlapping clock signals.

公开(公告)号：CA2437193C

公开(公告)日：2009-05-26

申请号：CA2437193

申请日：2002-01-30

Applicant: QUALCOMM INC

Inventor： BAZARJANI SEYFOLLAH ,  GOLDBLATT JEREMY

IPC: G05F3/26 ,  H03F3/45 ,  G05F3/08 ,  G05F3/20

Abstract: A bias circuit (126) is described for use in biasing an operational amplifie r (110) to maintain a constant transconductance divided by load capacitance (i.e. a constant gm/CL) despite temperature and process variations and despi te body effects. The bias circuit (126) includes a pair of current source devic es and a switched capacitor (SC) equivalent resistor circuit (136) for developi ng an equivalent resistance between the current source devices. By providing an SC equivalent resistor circuit clocked by non-overlapping fixed clock signal s, the gm/CL of the bias circuit is maintained substantially constant. Hence, a fixed bandwidth is maintained within the operation amplifier being biased. When employed in connection with operational amplifiers of an SC circuit, th e constant bandwidth enables the SC circuit to operate at a constant switching speed despite temp and process variation. Furthermore, by positioning the resistance equivalent circuit (136) between the current source devices of th e bias circuit, voltage differentials between the sources are eliminated there by removing any threshold voltage mismatch and thus compensating for body effec t variations.

公开(公告)号：CA2437193A1

公开(公告)日：2002-08-08

申请号：CA2437193

申请日：2002-01-30

Applicant: QUALCOMM INC

Inventor： BAZARJANI SEYFOLLAH ,  GOLDBLATT JEREMY

IPC: G05F3/26 ,  G05F3/20 ,  H03F3/45

Abstract: A bias circuit (126) is described for use in biasing an operational amplifie r (110) to maintain a constant transconductance divided by load capacitance (i.e. a constant gm/CL) despite temperature and process variations and despi te body effects. The bias circuit (126) includes a pair of current source devic es and a switched capacitor (SC) equivalent resistor circuit (136) for developi ng an equivalent resistance between the current source devices. By providing an SC equivalent resistor circuit clocked by non-overlapping fixed clock signal s, the gm/CL of the bias circuit is maintained substantially constant. Hence, a fixed bandwidth is maintained within the operation amplifier being biased. When employed in connection with operational amplifiers of an SC circuit, th e constant bandwidth enables the SC circuit to operate at a constant switching speed despite temp and process variation. Furthermore, by positioning the resistance equivalent circuit (136) between the current source devices of th e bias circuit, voltage differentials between the sources are eliminated there by removing any threshold voltage mismatch and thus compensating for body effec t variations.

公开(公告)号：WO02061519A2

公开(公告)日：2002-08-08

申请号：PCT/US0203012

申请日：2002-01-30

Applicant: QUALCOMM INC

Inventor： BAZARJANI SEYFOLLAH ,  GOLDBLATT JEREMY

IPC: G05F3/26 ,  G05F3/20 ,  H03F3/45

CPC classification number: G05F3/205

Abstract: A bias circuit (126) is described for use in biasing an operational amplifier (110) to maintain a constant transconductance divided by load capacitance (i.e. a constant gm/CL) despite temperature and process variations and despite body effects. The bias circuit (126) includes a pair of current source devices and a switched capacitor (SC) equivalent resistor circuit (136) for developing an equivalent resistance between the current source devices. By providing an SC equivalent resistor circuit clocked by non-overlapping fixed clock signals, the gm/CL of the bias circuit is maintained substantially constant. Hence, a fixed bandwidth is maintained within the operation amplifier being biased. When employed in connection with operationa amplifiers of an SC circuit, the constant bandwidth enables the SC circuit to operate at a constant switching speed despite temp and process variation. Furthermore, by positioning the resistance quivalent circuit (136) between the current source devices of the bias circuit, voltage differentials between the sources are eliminated thereby removing any threshold voltage mismatch and thus compensating for body effect variations.

Abstract translation: 描述偏置电路（126）用于偏置运算放大器（110），以保持恒定的跨导除以负载电容（即，恒定的gm / CL），尽管温度和工艺变化以及身体效应。 偏置电路（126）包括一对电流源装置和用于在电流源装置之间产生等效电阻的开关电容器（SC）等效电阻器电路（136）。 通过提供由非重叠固定时钟信号时钟的SC等效电阻电路，偏置电路的gm / CL保持基本恒定。 因此，在被偏置的运算放大器内维持固定带宽。 当与SC电路的放大器连接使用时，恒定带宽使得SC电路能够以恒定的开关速度工作，尽管温度和工艺变化。 此外，通过将电阻等效电路（136）定位在偏置电路的电流源装置之间，消除源之间的电压差，从而消除任何阈值电压失配，从而补偿体效应变化。