500-013 System Features:

	256 Channels
	Frequency Range of 0.8 - 1.25 MHz
	60 Watts Maximum Power Per Channel
	Forward and reflected power monitoring
	Proprietary Feed back Controlled Channel Independent Phase Shifting
	Unique integrated forward power feedback for precise power delivery
	RS-232 serial interface
	Rack mounted modular design

Overview

The 500-013 is a 256-channel high power, ultrasound phased-array transducer driver. Capable of delivering 60W per channel continuously from 0.8 MHz to 1.25 MHz with individual power control, the 500-013 is capable of driving a wide variety of ultrasonic devices. A precision power leveling circuit precisely delivers the desired forward power into the load, regardless of the load impedance (within the operating range of the amplifier). The precision power measurement capability allows the continual monitoring of the forward and reflected RF power. For high speed applications, such as hydrophone measurements, a voltage feedback mode of the amplifiers allows the production of pulses on the order of 10 cycles. Fault detection circuitry protects the amplifiers from a whole array of faults ranging from shorted outputs to badly mismatched or open circuit outputs.

Microcontrollers on each amplifier card continually monitor the operation of each amplifier (each microcontroller controls four amplifiers). Limits on forward and reflected power for each channel can be preprogrammed to either discontinue power or to alert the host computer, providing nearly instantaneous fault detection. A 250 element stack allows for the preprogramming of a series of independent phase settings and RF powers. Each stack element can be executed for accurate, preprogrammed time intervals.

Communication between the amplifier and host system is performed via an RS-232 serial port interface (optional RS-422 available). Communication can occur at up to 115.2 K baud, allowing wide bandwidth access to the amplifier system. The command structure is based on simple "English language" commands, to simplify the programming of the 500-013 Generator. A demo program which allows complete manual operation of the amplifier from a MS-Windows® based PC is included with the base system. To simplify development of custom applications, the source code is also included at no additional charge. Due to the generic nature of the RS-232 interface, virtually any platform may be used as a controller for the 500-013 amplifier system.

 

500-013 Specifications

Parameter	Value
Amplifier
Number of Channels	64
Frequency Range	0.8 - 1.25 MHz
Output Power per Channel	60 Watts Max.
Total RF Output Power	1800Watts
Power Control Resolution	8 bits (non-linear)
Power Control Accuracy	±5%
Power Measurement
Resolution	12 bits (<0.04 W)
Accuracy	±5%
Power Settling Time
Power Feedback	23 ms (60 Watts)
Voltage Feedback	10 ms (60 Watts)
Phase Control
Range	0-360
Resolution	1.5°  @ 0.8 MHz   2.3°  @ 1.25 MHz

Power Control

Each amplifier channel is integrated with a dual-directional coupler (DDC) allowing high precision monitoring of forward and reflected RF power. Each side of the DDC is connected to a high precision power meter, and the forward side power meter is inserted directly into the feedback loop of the amplifier. Power leveling based on the forward power is a unique feature of our amplifiers which allows for precise delivery of power to the ultrasound transducers.

While the actual power control is specified as 8 bits, nonlinear, the embedded controller allows the power to be set in terms of watts, rather than bit values.  Thus the actual bits of power control resolution are not seen by the user.

By using the microcontroller stack, the output power can be quickly varied to amplitude modulate the output signal, allowing for more flexible power delivery.

Phase Control

Channel independent phase control allows each amplifier to be set at any phase between 0 ° and 360 ° relative to the externally available system reference clock, regardless of the phase of any other channel in the system. The phase control circuitry precisely controls the phase after at the transducer surface, regardless of phase shifts caused by impedance matching circuitry. Phase, like power, can be quickly varied by utilizing the microcontroller stack to phase modulate the output signal, providing rapid switching of phase patterns over the entire system.

Intelligent Control and Monitoring

Each four amplifier channels include a dedicated microcontroller responsible for communicating with the main embedded controller, controlling output power and phase independently for each of the four channels, and monitoring the forward and reflected power delivered by each amplifier channel.

The embedded microcontrollers allow maximum and minimum values to be set for both the forward and reflected power for each channel. When these limits are exceeded, a flag is set indicating the specific channel is out of range. The system is capable of then either prompting for user intervention or executing the appropriate standard preprogrammed stack routine. For example, during an extended hyperthermia treatment period, one may select to set both minimum and maximum values for forward power to act as a secondary safety monitoring system to the hardwired amplifier power feedback control. Limits on reflected power can also be set in order to monitor load and matching status.

The microcontrollers also make possible rapid phase and power switching that would otherwise not be possible due to the limited rate of data transfer. In a system without this intelligent control, each time a parameter needs to be changed, the system controller must download the appropriate settings to the amplifier channel. Using on-card microcontrollers, these setting can be downloaded before treatment execution and placed in a non-volatile stack. Cycling through the stack is accomplished by toggling the state of a single, internal parallel line either manually or automatically via an integrated timer.

The entire amplifier system is controlled by an embedded PC which monitors the performance of the amplifiers and communicates with the host computer. The embedded PC off-loads the basic monitoring functions from the host computer. In turn, the embedded PC oversees the actual channel monitoring performed by the microcontrollers. This delegated network allows for real-time performance of an ultrasound driving system with many channels.

Safety

The network of distributed control allows for a much higher degree of safety than would otherwise be possible in a system with large number of channels. As the microcontrollers are directly integrated into the feedback network of the amplifiers, forward and reflected power can be measured and compared to preset limits hundreds of times each second. Should the measured power deviate beyond the preset limits, the microcontroller can either automatically, immediately shut down the amplifier channel or simply prompt for user intervention. As every channel is considered independently, all channels need not have the same limits nor respond to over-limit conditions with the same action.

The microcontrollers and the embedded controller all include watch-dog timers to insure no unwanted power delivery.

System Architecture

The figure shown below illustrates a single channel of the ultrasound driving system. Each microcontroller actually controls four driving channels, and controls the power and phase of the driving system. Dual directional couplers measure the forward and reflected power which is continuously monitored by the microcontroller. A unique feature of the driving system is that the output power is controlled by programming the forward power, which is the basis for the feedback rather than a voltage. This is very useful for therapeutic ultrasound drivers since the deposited power is directly proportional to the RF power, while the output power at a constant voltage can vary from transducer to transducer. The electrical signal is then isolated by the isolation transformer.

The amplifiers are controlled by a single board embedded computer. The function of this computer is to handle all of the interfacing between the host system and the amplifiers as well as the monitoring and safety aspects of the operation.

Single Channel Block Diagram

System Programming/Interfacing

Control of the 500-013 system is accomplished by standard asynchronous RS-232 transmission to and from an external controlling computer (PC, Sun Station, etc.) In addition, several parallel lines allow direct access to system features such as parallel reset, monitor power, and cycle stack triggers. Included with the base system is a Microsoft Windows® based interface to the 500-013. This program allows programming of all basic features of the system, including the stack capabilities for rapid switching and data logging. To ease in configuring a custom interface, the source code for this interface is included at no extra charge. In addition, Advanced Surgical Systems will work with its customers for software development.

Warranty and Support

The 500-013 will be warranted for a period of one year, including all parts and labor, providing the system is operated within the specified operating range. Additionally, Advanced Surgical Systems is willing to work with its customers to make sure that the equipment is used to its maximum potential, whether this be regarding interfacing with the transducers, developing control software, or any other issues that may arise throughout the lifetime of the 500-013 system. Throughout the life of the product, technical support is available at no charge.

Pricing

The systems as quoted consist only of the systems described herein. Any modifications may affect the actual pricing. Please be advised that the pricing information shown here is not to be considered a formal quote. For a formal quote, please contact Advanced Surgical Systems, Inc.

Description	SKU #	Price
500-013 Generator	500-013	$CALL