Modular Approach Provides Fast And Easy Prototyping

Prototype development of RF and microwave designs can be tedious, requiring weeks or even months of engineering and construction time. For those who seek a faster, easier approach to the prototyping of new RF and microwave designs, however, MicroWaveCells (www.microwavecells.com) offers a new and innovative approach to building high-frequency circuit functions, subsystems, and complete systems in hours and days, rather than in weeks and months, at a fraction of the cost of traditional prototyping efforts. The new prototyping method is based on a patented fast RF and microwave circuit design and and prototyping concept in which designs are created from standard single-function printed-circuit-board (PCB) cells. The single-function-cell approach can also be applied to the development of component modules that can be readily modified in terms of choice of connectors, number of input and output ports, bias arrangement, and even such mechanical details as a mounting bracket.

The prototyping approach is elegant in its simplicity. It involves a combination of electrical function blocks with mechanical or package function blocks to create a final assembly that can be a single function, such as an amplifier, or a combination of building-block functions, such as amplifiers, filters, mixers, and oscillators to form a receiver front end. The mechanical modules provide protection for the electrical circuitry and allow customers to specify the precise dimensions, inputs and outputs, and other connections for their prototype. By using the dynamic sidewall concept developed by MicroWaveCells, customers can build a mechanical module in minutes based on preferences for power-supply and RF connections, size, package materials, and other choices. This rapid and dynamic prototyping concept saves much time and money compared to the traditional RF/microwave prototyping cycles.

To facilitate the prototype design process, the company has fabricated a range of single-function PCB cells, including more than 20 different amplifier cells, more than 15 different mixer cells, several attenuators, voltage-controlled oscillators (VCOs), filters, detectors, couplers, splitters, prescalers, multipliers, phase shifters, DC blocks, transitions and launches, and voltage regulators. Mechanical cells include a range of single mechanical cells (for single-function designs), 5 x 5 array mechanical cells for joining a variety of different functions in a subsystem prototype, and dynamic mechanical cells.

MicroWaveCells designs a standard single cell with dimensions of 20 x 20 mm²Fig. 1(a)>. All single cells follow the standard layout rules such as common input and output locations, common mounting positions, common DC/ control connector at a predefined location, etc. If a single cell cannot fit for a device footprint with its application circuit, a multiple cell size, such as a 2 x 3 cell footprint, can be used. For example, Fig. 2 shows a frequency synthesizer PCB using a 2 x 3 cell size (measuring 40 x 60 mm²). The company offers hundreds of single-function PCB cells covering 21 different application categories and equivalent to thousands of the most common off-the-shelf RF/microwave components from leading suppliers.

In addition to standard PCB cells, MicroWaveCells has also developed standard mechanical cells as mounting and packaging options for the PCB cells Fig. 1(b)>. These mechanical building blocks can be extended to custom sizes as required. Designers can use these cells to build and test each single-cell function with corresponding single-cell mechanics. Some cells/functions have more than one single-cell dimension, such as the synthesizer cell with a 2 x 3 cell shown in Fig. 2(b). Integrated single-cell modules and 2(c)> support most key RF functions with frequency range extending from DC to 40 GHz.

The firm's patented dynamic single- module concept is based on designs using the standard single cell product line. The single mechanical cell is designed to be connected by means of sidewalls and covers of a customer's choosing. By making these mechanical/packaging choices online, a customer can create a singlefunction module within minutes using the MicroWaveCells prototyping approach. Figure 3 offers an example of how a customer quickly assembled a dynamic single-function module with the MicroWaveCells approach, by combining a standard cell with specific custom packaging requirements.

The single cell approach can be extended to any dimension and any shape by using the single-cell base module and single-cell base joint. A half-cell base can be added for the side input or output launch. Figure 4 shows the front and the back sides of a dynamic multicell subsystem example.

As an example of a higher-level design using the MicroWaveCells approach, Fig. 5 shows the block diagram for a transmitter based on custom filtering, mixer-based frequency upconversion, and phase-lock-loop (PLL) frequency synthesis. By no means a trivial design, this project can be assembled with available single-function PCB cells from MicroWaveCells into the prototype shown in Fig. 6(b). Then, using single mechanical cells and cell joints, the mechanical part of the prototyping project can be completed to form the assembly shown in Fig. 6(b). The output filter in this transmitter is a custom 1 x 2 cell developed by the customer for this transmitter prototype. For bias and control convenience, MicroWaveCells also offers a 1 x 5 DC management cell. Figure 7 shows the front and back sides of the assembled system using this dynamic cell concept. To minimize cost and simplify integration, MicroWaveCells also offers a 5 x 5 dynamic array mechanical cell module that can be used to assemble larger system concepts in short order (Fig. 8 and 9). By adding a uniform sidewall (model M-AW01A) and a cover (model M-AV01A), it is possible to assemble an enclosed system with a 5 x 5 array of by combining several 5 x 5 array modules. Each array sidewall supports a maximum of 5 SMA input ports, three DC bias connections, and two mounting brackets.

This prototyping approach can help RF/microwave companies shave development times and costs. The combination of standard PCB function cells and dynamic standard mechanical cells helps build a prototype design quickly and reduce R&D costs.