2 transistor buffer

When designed with general-purpose small-signal transistors, the bandwidth ranges from 50 MHz to 250 MHz, necessitating careful grounding and power supply decoupling. The simulation schematic illustrates a two-transistor buffer. Due to copyright issues, models from other sources are not included here and can be downloaded from the manufacturers' websites. The signal generator is configured as VIN 101 0 AC 1 SINE(0 5 1000 0 0 0). The power supply voltage is Vcc 30. The load resistor value is defined as PARAM Rl=10K, with a step parameter for Rl listed as 100, 1000, and 10000. A 100-ohm load resistance is included to highlight the clipping of the single transistor circuit, where crossover distortion is notably high for the two-transistor circuit. The single transistor buffer is configured with R111 101 11 1 as the series resistor from the generator, C11 11 12 10u, R11 Vcc 12 47K, R12 12 0 47K, and Q11 Vcc 12 13 ZTX653. For R13 13 0, a 3K resistor is used, and C12 13 14 is 220u, with R14 14 0 set to {Rl}. The two-transistor buffer, utilizing a single supply, features R121 101 21 1 as the series resistor from the generator, C21 21 22 10u, R21 Vcc 22 47K, R22 22 0 47K, Q21 Vcc 22 24 ZTX653, and R23 24 0 at 5.9K. Q22 is connected from 0 to 22 and 23 as ZTX753, with R24 Vcc 23 at 5.9K. Capacitors C22 23 25 and C23 24 25 are both 100u, and R25 25 0 is defined as {Rl}. The DC temperature is set to 70, and AC DEC is configured from 10 to 1 MEG. Noise analysis is performed on V(25) VIN with DEC set from 10 to 100K, and transient analysis is set to 2m. The schematic concludes with a probe command.

The circuit design described utilizes small-signal transistors to create a buffer configuration that operates effectively within a specified bandwidth of 50 MHz to 250 MHz. The careful attention to grounding and power supply decoupling is crucial in high-frequency applications to minimize noise and ensure signal integrity.

The simulation schematic includes a signal generator configured to provide a sine wave input, which is essential for testing the frequency response and dynamic behavior of the buffer circuit. The use of a variable load resistor allows for the examination of how different load conditions affect the performance of the buffer, particularly in terms of linearity and distortion characteristics.

The inclusion of both a single transistor buffer and a two-transistor buffer in the design allows for a comparative analysis of their performance. The single transistor buffer is simpler and may introduce higher crossover distortion, especially under lower load conditions, while the two-transistor configuration offers improved performance by reducing distortion and enhancing linearity.

Power supply considerations are addressed with a defined voltage of 30 Vcc, and the use of decoupling capacitors at critical points in the circuit is vital for stabilizing the power supply and reducing the effects of voltage fluctuations on the performance of the transistors.

Overall, this circuit schematic provides a comprehensive framework for analyzing the characteristics of small-signal transistor buffers, allowing for adjustments and optimizations based on specific application requirements. The simulation parameters set forth will enable detailed insights into the circuit's behavior under various conditions, facilitating effective design and implementation in practical scenarios.When designed with general purpose small-signal transistors, the bandwidth is 50MHz to 250MHz so very careful grounding and power supply decoupling is required. Simulation schematic for 2 transistor buffer. *Copyright Poul Petersen 2009 * *Some standard Spice stuff. Due to copyright issues models from other sources are not *included here. They can be downloaded from the manufacturers` *web sites. . Lib C:LIBsSpiceetex_dl. lib * *Signal generator VIN 101 0 AC 1 SINE(0 5 1000 0 0 0) * *Power supply Vcc Vcc 0 30 * *Load resistor value. PARAM Rl=10K. STEP PARAM Rl LIST 100 1000 10000 *100R load resistance is included to emphasize the clipping of the *single transistor circuit.

Cross over distortion is very high into *100R for the 2 transistor circuit. * *Single transistor buffer. R111 101 11 1 ; Series resistor from generator. C11 11 12 10u R11 Vcc 12 47K R12 12 0 47K Q11 Vcc 12 13 ZTX653 ; from R13 13 0 3K C12 13 14 220u R14 14 0 {Rl} * *2 Transistor buffer with single supply. R121 101 21 1 ; Series resistor from generator. C21 21 22 10u R21 Vcc 22 47K R22 22 0 47K Q21 Vcc 22 24 ZTX653 ; from R23 24 0 5. 9K Q22 0 22 23 ZTX753 ; from R24 Vcc 23 5. 9K C22 23 25 100u C23 24 25 100u R25 25 0 {Rl} * ;. DC TEMP 0 70 10. AC DEC 10 100m 1MEG ;. NOISE V(25) VIN DEC 10 10 100K ;. TRAN 2m. PROBE. END * 🔗 External reference