The AMC7908EVM is an easy-to-use platform to evaluate the functionality and performance of the AMC7908 device. The AMC7908EVM has optional circuits and jumpers to configure the device for different applications.

The AMC7908 is a highly integrated power-amplifier monitor and control device with eight 13-bit digital-to-analog converters (DAC) and a 12-bit analog-to-digital converter (ADC). The DACs can be switched on and off through dedicated clamping software and hardware triggers.

1. Order the EVM.
2. Configure EVM jumpers.
3. Install the AMC7908EVM GUI from ti.com.
4. Download the latest libraries.
5. Connect USB and external power supplies.
6. Launch the AMC7908EVM GUI.

• Configurable circuit to evaluate the AMC7908
• Onboard VDD (5V) and VIO (3.3V) support via USB
• Onboard VSSA and VSSB (−10.5V or −7V) support
• FT4222 easily writes to the AMC using the AMC7908EVM GUI
• External SPI and I²C connections available

• Macro remote radio unit (RRU)
• Active antenna system mMIMO (AAS)
• Outdoor backhaul unit
• Radar

The AMC7908 is a highly integrated power-amplifier monitor and control device capable of temperature, current, and voltage supervision. The AMC7908 bias controller features eight digital-to-analog converters (DAC) with programmable output ranges. The eight gate bias outputs are switched on and off through dedicated control pins.

The AMC7908 supervisor also features a highly accurate multichannel analog-to-digital converter (ADC). The device integrates two high-voltage inputs, two high-side current-sense amplifiers, and an on-chip temperature sensor.

The function integration and wide operating temperature range make the AMC7908 an excellent choice for an all-in-one, bias control circuit for the power amplifiers found in RF communication systems.

This user's guide describes the characteristics, operation, and recommended use cases of the AMC7908EVM. This document provides examples and instructions on how to use the AMC7908EVM board and included software. Throughout this document, the terms evaluation board, evaluation module, and EVM are synonymous with the AMC7908EVM. This document also includes schematics, the reference printed circuit board (PCB) layouts, and a complete bill of materials (BOM).

Table 2-1 details the contents of the EVM kit. Contact the TI Product Information Center at (972) 644-5580 if any component is missing. Download the latest versions of the related software on the TI website, www.ti.com.

The documents in Table 2-2 provide information regarding Texas Instruments integrated circuits used in the assembly of the AMC7908EVM. This user's guide is available from the TI web site under literature number SLAU883. Any letter appended to the literature number corresponds to the document revision that is current at the time of the writing of this document. Newer revisions are available from the TI web site at www.ti.com, or call the Texas Instruments Literature Response Center at (800) 477-8924 or the Product Information Center at (972) 644-5580. When ordering, identify the document by both title and literature number.

This section describes the overall system setup for the EVM. A PC runs software that communicates with the FTDI controller onboard using I²C or SPI protocols. External power supplies are required for certain EVM inputs, such as the VCCA and VCCB supplies.

The AMC7908EVM is connected to the computer through the on-board FTDI digital controller using the USB cable that is supplied with the EVM. The evaluation board features connectors and test points for all communication lines, DAC outputs, supplies, and the ADC inputs. Figure 3-1 shows a block diagram of the AMC7908EVM.

Figure 2-1 Theory of Operation Block Diagram

The USB connection provides the 5V supply to the EVM. A voltage regulator generates 3.3V from the USB 5V supply. These 5V and 3.3V supplies are used to power the FTDI controller.

The AMC7908 VDD supply can use the on-board 5V supply depending on the J13 pins 3-4 setting. By default, the VDD supply is connected to the on-board 5V supply. Alternatively, VDD can be supplied externally through banana jack J5. Remove the jumper connector on J13 pins 3-4 before connecting external supplies to VDD.

The AMC7908 VIO supply can use the on-board 3.3V supply depending on the J13 pins 1-2 setting. By default, the VIO supply is connected to the on-board 3.3V supply. Alternatively, VIO can be supplied externally through banana jack J8. Remove the jumper connector on J13 pins 1-2 before connecting external supplies to VIO.

The AMC7908 VCCA and VCCB supplies are used to configure the device to operate in the positive output range. If using the positive range, then power VCCA and VCCB externally using banana jacks J3 and J11, respectively. If using the negative range, then place a shunt on pins 1-2 of J2 and J9 to connect VCCA and VCCB to ground. Jumper J6 can be used to connect VCCA and VCCB together, allowing for the use of one external supply to power both VCCA and VCCB. Remove the jumper connections on pins 1-2 of J2 and J9 before connecting external supplies to VCCA or VCCB, respectively.

The AMC7908 VSSA and VSSB supplies are used to configure the device to operate in the negative output range. If using the negative range, then VSSA and VSSB can be powered externally using banana jacks J4 and J12, respectively. Alternatively, an on-board voltage regulator is available to provide negative voltage to the supplies. The regulator is powered by an external negative power supply, VNEG, and can output either –7 V or –10.5 V depending on the position of jumper J28. Jumper J29 connects the on-board negative voltage to the VSSA and VSSB supplies. If using the positive range, place a shunt on pins 2-3 of J2 and J9 to connect VSSA and VSSB to ground. Remove the jumper connections on J29 and pins 1-2 of J2/J9 before connecting external supplies to VSSA and VSSB.

There are multiple unpopulated components on the EVM that can be populated to change the configuration of the EVM:

• R7 and R9 are I²C pull-ups to VIO. When using a communication source other than the FTDI controller for I²C communication, R7 and R9 can be populated for pull-ups to VIO.
• C6, C11, C18, and C20 are 0603 footprints to allow for larger capacitance loads on the DACA1, DACA3, DACB1, and DACB3, respectively.
• J14, J15, J20, J21, J26, and J27 are optional terminal blocks. See Table 3-4 for more information.

Table 3-1 provides the details of the configurable jumper settings of the AMC7908EVM. Figure 3-2 shows the default jumper connections on the board.

Figure 2-2 AMC7908EVM Default Jumpers