Amplification circuit with read/write circuit
The invention relates to an amplification circuit ( 100 ), comprising: a VGA ( 2 ), an AGC loop ( 10 ) for automatically controlling the gain of the VGA ( 2 ), a switching circuit ( 14 ) for switching between an AGC mode, in which the gain of the VGA ( 2 ) is automatically controlled by an output signal of the AGC loop ( 10 ) and a manual gain control, MGC, mode, in which the gain of the VGA ( 2 ) can be manually controlled by an input signal, and a read/write circuit ( 30 ) with a contact ( 31 ) for connection to a peripheral system, wherein the read/write circuit ( 30 ) is configured, in the MGC mode, to provide the input signal from the contact ( 31 ) via a write-mode path ( 32 ) to the VGA ( 2 ), and, in the AGC mode, to provide the output signal of the AGC loop ( 10 ) via a read-mode path ( 33 ) on the contact ( 31 ).
1. An amplification circuit, comprising:
a variable gain amplifier, VGA,
an automatic gain control, AGC, loop for automatically controlling the gain of the VGA,
a switching circuit for switching between an AGC mode, in which the gain of the VGA is automatically controlled by an output signal of the AGC loop and a manual gain control, MGC, mode, in which the gain of the VGA can be manually controlled by an input signal, and
a read/write circuit with a contact for connection to a peripheral system, wherein the read/write circuit is configured, in the MGC mode, to provide the input signal from the contact via a write-mode path to the VGA, and, in the AGC mode, to provide the output signal of the AGC loop via a read-mode path on the contact.
2. The amplification circuit as defined in claim 1 , wherein the switching circuit comprises a selection signal input for inputting a selection signal for selecting the AGC mode or the MGC mode.
3. The amplification circuit as defined in claim 2 , wherein the read-mode path comprises a circuit that is configured to act as a unity gain buffer when the AGC mode is selected by the selection signal.
4. The amplification circuit as defined in claim 3 , wherein the circuit is further configured to switch off the read-mode path when the MGC mode is selected by the selection signal.
5. The amplification circuit as defined in claim 4 , wherein the circuit comprises an operational amplifier and an inverter circuit forming a negative feedback loop across the operational amplifier.
6. The amplification circuit as defined in claim 5 , wherein the inverter circuit is configured to be disabled when the MGC mode is selected by the selection signal.
7. The amplification circuit as defined in claim 6 , wherein the inverter circuit comprises a CMOS inverter comprises a PMOS transistor connected to an NMOS transistor and additional switches that are configured to switch off the CMOS inverter from a supply voltage and from ground when the MGC mode is selected by the selection signal.
8. The amplification circuit as defined in claim 7 , wherein the circuit comprises a switch that is configured to switch off the operational amplifier from a bias current when the MGC mode is selected by the selection signal.
9. The amplification circuit as defined in claim 8 , wherein the write-mode path comprises a switch that is configured to switch off the write-mode path when the AGC mode is selected by the selection signal.
10. A method for operating an amplification circuit as defined in claim 1 , comprising:
in the MGC mode, providing the input signal from the contact via the write-mode path to the VGA, and
in the AGC mode, providing the output signal of the AGC loop via the read-mode path on the contact.
11. The amplification circuit as defined in claim 3 , wherein the circuit comprises an operational amplifier and an inverter circuit forming a negative feedback loop across the operational amplifier.
12. The amplification circuit as defined in claim 11 , wherein the inverter circuit is configured to be disabled when the MGC mode is selected by the selection signal.
13. The amplification circuit as defined in claim 12 , wherein the inverter circuit comprises a CMOS inverter comprising a PMOS transistor connected to an NMOS transistor and additional switches that are configured to switch off the CMOS inverter from a supply voltage and from ground when the MGC mode is selected by the selection signal.
14. The amplification circuit as defined in claim 5 , wherein the circuit comprises a switch that is configured to switch off the operational amplifier from a bias current when the MGC mode is selected by the selection signal.
15. The amplification circuit as defined in claim 2 , wherein the write-mode path comprises a switch that is configured to switch off the write-mode path when the AGC mode is selected by the selection signal.