Method and apparatus for compensating for gain changes in an amplifier circuit
View Patent ↗In a method and apparatus for compensating for gain changes in an amplifier circuit comprising radio-frequency modules and attenuation elements, a radio-frequency module is driven with a first temperature-dependent monitoring voltage U HF (T), and an attenuation element with a second temperature-dependent monitoring voltage U VG (T). The first temperature-dependent monitoring voltage U HF (T) is produced by applying a temperature dependency to an individual monitoring voltage U opt , which is predetermined for a predetermined temperature for a radio-frequency module, in order to set the optimum operating point of the radio-frequency module. The second temperature-dependent monitoring voltage U VG (T) is produced by applying a temperature dependency to a predetermined monitoring voltage U VG — T for the attenuation element. The monitoring voltage U VG — T is determined in an iteration method, such that the output power of the amplifier circuit reaches a predeterminable level at a constant input power. Memory devices are provided for storing values for producing monitoring voltages for the radio-frequency modules and attenuation elements.
1. A method of compensating for gain changes in an amplifier circuit, comprising radio-frequency modules and attenuation elements, said method comprising:
driving a radio-frequency module with a first temperature-dependent monitoring voltage U HF (T), and an attenuation element with a second temperature-dependent monitoring voltage U VG (T); wherein,
the first temperature-dependent monitoring voltage U HF (T) is produced by applying a temperature dependency to an individual monitoring voltage U opt , which is predetermined for a predetermined temperature for a radio-frequency module, to set the optimum operating point of the radio-frequency module;
the second temperature-dependent monitoring voltage U VG (T) is produced by applying a temperature dependency to a predetermined monitoring voltage U VG — T for the attenuation element; and
the monitoring voltage U VG — T is determined by an iteration method such that the output power of the amplifier circuit reaches a predeterminable level at a constant input power.
2. The method as claimed in claim 1 , wherein the value of the monitoring voltage U opt is converted to a division ratio, and is read to a first memory device.
3. The method as claimed in claim 1 , wherein a value of the determined monitoring voltage U VG — T which corresponds to the ratio of the output power to the input power of the amplifier circuit is converted to a division ratio, and is read to a second memory device.
4. The method as claimed in claim 1 , wherein a power amplifier is driven with a temperature-dependent monitoring voltage U LV (T).
5. The method as claimed in claim 4 , wherein the power amplifier is driven with a pulsed monitoring voltage U LV (T).
6. An apparatus for compensating for gain changes in an amplifier circuit comprising radio-frequency modules and attenuation elements, said apparatus comprising:
memory devices for permanent storage of values for producing monitoring voltages for the radio-frequency modules and attenuation elements; and
electrical circuits having an input and an output for producing a temperature-dependent output voltage taking account of a temperature-dependent input voltage U AcT (T), which is applied to the electrical circuits, and a value which is stored in the memory devices, wherein,
the stored value corresponds to an individual monitoring voltage U opt for setting the optimum operating point of the radio-frequency modules;
each radio-frequency module and each attenuation element has an associated memory device; and
the apparatus further comprises an output power amplifier and a resistance network for producing a monitoring voltage for the output power amplifier.
7. The apparatus as claimed in claim 6 , having an electrical control circuit comprising:
a temperature sensor; and
an operational amplifier connected downstream from the temperature sensor, for producing the temperature-dependent voltage U ACT (T).
8. The apparatus as claimed in claim 7 , wherein said temperature sensor comprises one of a diode, a transistor and an integrated circuit.
9. The apparatus as claimed in claim 7 , wherein the resistance network comprises negative temperature-coefficient resistors.
10. The apparatus as claimed in claim 6 , wherein the memory devices and electrical circuits are integrated in a digital potentiometer, with an input for supplying a temperature-dependent input signal U ACT (T) as well as outputs which are respectively associated with a radio-frequency module and an attenuation element.
11. The apparatus as claimed in claim 10 , wherein the memory device, the electrical control circuit and the digital potentiometer are integrated in an application-specific integrated circuit.
12. The apparatus as claimed in claim 11 , wherein the memory devices and electrical circuits are integrated in a digital potentiometer, with an input for supplying a temperature-dependent input signal U AcT (T) as well as outputs which are respectively associated with a radio-frequency module and an attenuation element.
13. The apparatus as claimed in claim 12 , the memory device, the electrical control circuit and the digital potentiometer are integrated in an application-specific integrated circuit.