A radio frequency load drive circuit

Abstract

The invention relates to the field of communication and discloses a radio frequency load driving circuit. In the present invention, it includes: L NMOS tubes and M PMOS tubes, L is a natural number greater than 1, M is a natural number, and L is greater than or equal to M; L NMOS tubes are connected in cascode; when M is equal to 1, The PMOS transistors are connected in a common source mode; when M is greater than 1, the M PMOS transistors are connected in cascode; the gate of the PMOS transistor whose source is connected to the power supply is connected to the first input voltage, and the gate of the NMOS transistor whose source is grounded The pole is connected to the second input voltage; the drain of the NMOS transistor connected with the drain of the PMOS transistor is the output end; the gates of the other PMOS transistors are connected to their respective bias voltages, and the gates of the PMOS transistors The bias voltages of the NMOS transistors form the first set of bias voltages, the gates of the remaining NMOS transistors are connected to their respective bias voltages, and the bias voltages of the gates of the NMOS transistors form the second set of bias voltages. The invention improves the withstand voltage value and conversion efficiency of the circuit, and also improves the linearity of the circuit.

Description

technical field [0001] The invention relates to the communication field, in particular to a radio frequency load driving circuit. Background technique [0002] Existing RF load drive circuits such as figure 1 As shown, 101 is a radio frequency load driving circuit, 102 is a radio frequency load, 103 is a choke inductor, the radio frequency load driving circuit is composed of an NMOS tube (or other types of transistors) 1011, VDD is the power supply voltage, V IN for the input signal. Due to the low withstand voltage value of the NMOS transistor 1011 , the output voltage swing thereof is relatively small, and sufficient output power cannot be obtained for a given radio frequency load. [0003] At present, a solution to the above-mentioned problem is to connect a radio frequency load impedance transformation network in series between the radio frequency load driving circuit 101 and the radio frequency load 102, so that the radio frequency load driving circuit can drive the r...

AI Technical Summary

Problems solved by technology

When the static gate-source voltage is high and the input signal is small, I D Near the static working point, it can be regarded as I D With V GS Linear change, the transconductance of the class A working range is close to a fixed value, which is equivalent to a linear working range, but this range is too small; the usual linear power amplifier works in the AB class working range, but I D nor with V GS varies linearly, the amplifier exhibits a non-linear

In addition, due to the higher static gate-source bias voltage, the efficiency is lower, from image 3 It can be seen that the linearity of Class A RF load driving circuits is the highest, but the efficiency is the lowest; the linearity of Class B and Class C RF load driving circuits is very low, but the efficiency is high; the linearity and efficiency of Class AB RF load driving circuits are moderate. made a compromise

[0008] One solution to solve the problem that the linear range of the Class A RF load driving circuit is too small, the efficiency is low, and the linearity of the Class AB working range is poor is to use a pseudo-differential structure RF load driving circuit, specifically as Figure 4 As shown, 401 is a radio frequency load driving circuit, 402 is a radio frequency load, 4031 and 4032 are choke inductors, and the radio frequency load driving circuit 401 is composed of NMOS transistors (or other types of transistors) 4011 and 4012. respectively input signal differential V IN1 with V IN2 , the transfer characteristic curve between the output current and the input voltage of the unit is as follows Figure 5 As shown by the solid line 501, the dotted line 502 is a comparison straight line; the vicinity of the origin can be regarded as a linear change area, from Figure 5 It can be seen that the range of the linear interval has increased, but the range is still small. When the input signal becomes larger, the output current increases linearly and then decelerates. When the amplifier is close to saturation, its output current changes slowly. , until it no longer increases with the increase of the input signal

Such linearity does not meet the actual needs

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