14 Measurements

要使用Mini-Circu进行测量its SSG-4000HP as the signal generator (Figure 5). Power measurements were made using Mini-Circuits PWR-SEN-8GHS USB power meters. Attenuation control to simulate signal fading was made using a Mini-Circuits RCDAT-6000-90. The signal generator was set to 900 MHz and the output power to +2 dBm. Following the output of the signal generator, the RF path was split using a Mini-Circuits ZX10-2-252-S+ power splitter. One arm of the power splitter attached to the SKY12325-350LF DSA. The other arm of the power splitter was connected to the RCDAT controllable attenuator. This arm was then connected to the TSY-13LNB+ LNA. The output of the TSY-13LNB+ was connected to another Mini-Circuits PWN-SEN-8GHS power sensor. A GreenPAK Advanced evaluation board and SLG46582-DIP module were used for the bias controller emulation. A Klein Tools DVM was inserted into the supply line for the PHA-23LN+ to measure the bias current. Each RF path was measured without the circuit in place and offsets entered into the power meters to set the reference to 0 dBm. This allows us to see the gain of the RF circuits. The setup is shown in Figure 6.

Figure 5: Signal Generator Setup

Figure 6: Setup

The wiring from the RaspberryPi controller is shown in Figure 7 below.

Figure 7: The Wiring from the RaspberryPi Controller

In low power mode, the PHA-23LN+ drew 65.7 mA at 3.0 V. This is slightly lower than the data sheet specification of 72.4 mA. At 5 V bias, the PHA-23LN+ drew 131.4 mA. The spec calls out 141.7 mA (see Figure 8).

Figure 8: Measurements

In low power mode the PHA-23LN+ output 12.24 dBm of power. The digital step attenuator has approximately 7 dB of attenuation. Since our input power is normalized to 0 dBm, this gives us approximately 19.24 dB gain. The spec sheet calls out 19.7 dB of gain at 3 V. This is close for what is really an uncalibrated setup. The LNA path is showing almost 3 dB of loss. The spec for the TSY-13LNB+ in bypass mode is about 1.9 dB of loss (see Figure 9). The approximately 1 db remaining loss is due to the detector circuit (as mentioned before it is not an ideal design).

Figure 9: Attenuation Measurement (0.00 dB)

In high power mode, the PHA-23LN+ output +20.28 dBm of power. The attenuator has approximately 0.8 dB of attenuation at minimum attenuation. This equates to 21.08 dB of gain. The spec at 5 V is 21 dB. The relative improvement in signal from low power to high power, we see an improvement of 8 dB of power with at 5 V. This makes sense since the attenuator has approximately 7 dB of attenuation at low power and the PHA-23LN+ has an extra dB of gain at 5 V vs. 3 V.

These first example image shows the performance with the LNA disabled. This is the point at which the high-power mode of the circuit became enabled. 11 dB of additional attenuation has been added to the LNA path dropping the detector voltage (see Figure 10).

Figure 10: Attenuation Measurement (11.00 dB)

With the LNA enabled, we see the following performance at high power. The LNA is providing approximately 14.98 dB of gain. This is slightly better than the typical specification performance numbers (see Figure 11).

Figure 11: Attenuation Measurement (11.00 dB, LNA enabled)

Decreasing the attenuation, the circuit shifts back to lower power mode around the 6 dB mark. There is approximately 5 dB of hysteresis in the RF power range. This has to do with the performance characteristics of the comparators in the GreenPAK IC. See Figure 12 on GreenPAK performance.

Figure 12: Attenuation Measurement (6.00 dB)

接下来,如图13所示,它是想测试工程师t the temperature monitoring performance of the SLG46582 bias controller. For this example, the Comparator3 trip level was changed from 1000 mV to 1050 mV. This equates to a temperature of about 85 °C vs 95 °C. This was done to prevent damage to the circuits but show how this safety feature performs. A heat gun was used to heat up the circuitry. As can be seen, the Temp Fault flag shows red. The DC voltage to the amplifiers was completely cut off until the circuit cooled. Once cooled, operations resumed as normal.

Figure 13: Attenuation Measurement (0.00 dB, 1050 mV)